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I created a calendar with the flatpickr.js library. I want to enable only the dates that are present in the arreys dateCorfu, dateZante and datePag selected from a dropdown (with the attribute name="destinazione").
I'm not a coder but I wrote the below code using the eval method, this is working but I'm sure that this is the wrong way.. maybe there is a better way to manipulate the result of function(date). So is there a way to make this to works without using eval?
flatpickr("#data-partenza", {
locale:'it',
minDate: "2020-07-16",
enable: [
function(date) {
// return true to enable
var drop_destinazione = jQuery('[name="destinazione"]').val();
var result = '';
var dateCorfu = ["2020-07-16","2020-07-23","2020-07-30","2020-08-06","2020-08-13","2020-08-20"];
var dateZante = ["2020-07-17","2020-07-24","2020-07-31","2020-08-07","2020-08-14"];
var datePag = ["2020-07-18","2020-07-25","2020-08-01","2020-08-08"];
var slice = 'date.toISOString().slice(0,10)';
var i;
if(drop_destinazione == 'Corfù'){
for (i = 0; i < dateCorfu.length; i++) {
result += (slice + '==' + '"' + dateCorfu[i] + '"' + '||');
}
return eval(result.slice(0, -2));
}
else if(drop_destinazione == 'Zante'){
for (i = 0; i < dateZante.length; i++) {
result += (slice + '==' + '"' + dateZante[i] + '"' + '||');
}
return eval(result.slice(0, -2));
}
else if(drop_destinazione == 'Pag'){
for (i = 0; i < datePag.length; i++) {
result += (slice + '==' + '"' + datePag[i] + '"' + '||');
}
return eval(result.slice(0, -2));
}
else {
console.log('no destination selected')
}
}
],
dateFormat: "d-m-Y",
disableMobile: true,
});
since you are only doing if-validations, why dont you just immediately evaluate and accumulate at each result += ..?
result = false;
for (...) {
if (condition) result = true;
}
return result;
or even better: exit early like this:
result = true;
for (...) {
if (condition) return true;
}
return false;
applied to your original code this would make your function look like this:
function(date) {
var drop_destinazione = jQuery('[name="destinazione"]').val();
var dateCorfu = ["2020-07-16","2020-07-23","2020-07-30",
"2020-08-06","2020-08-13","2020-08-20"];
var dateZante = ["2020-07-17","2020-07-24","2020-07-31",
"2020-08-07","2020-08-14"];
var datePag = ["2020-07-18","2020-07-25","2020-08-01","2020-08-08"];
var slice = date.toISOString().slice(0, 10);
if (drop_destinazione == 'Corfù') {
for (var i = 0; i < dateCorfu.length; i++) {
if (slice == dateCorfu[i]) return true;
}
}
else if(drop_destinazione == 'Zante') {
for (var i = 0; i < dateZante.length; i++) {
if (slice == dateZante[i]) return true;
}
}
else if(drop_destinazione == 'Pag') {
for (var i = 0; i < datePag.length; i++) {
if (slice == datePag[i]) return true;
}
}
else { console.log('no destination selected'); }
return false;
}
however there are steps you can take to make your code less repetitive:
function(date) {
var drop_destinazione = jQuery('[name="destinazione"]').val();
var slice = date.toISOString().slice(0, 10);
var allowed = {
Corfù: ["2020-07-16","2020-07-23","2020-07-30",
"2020-08-06","2020-08-13","2020-08-20"],
Zante: ["2020-07-17","2020-07-24","2020-07-31",
"2020-08-07","2020-08-14"],
Pag: ["2020-07-18","2020-07-25","2020-08-01",
"2020-08-08"],
};
if (allowed[drop_destinazione] == undefined) {
console.log('no destination selected');
return false;
}
return allowed[drop_destinazione].indexOf(slice) !== -1;
}
of course the property name "Corfù" does not look too nice, however "drop_destinazione" seems to be a dropdown, these have both a value and a label (see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/select). you should make the values simple strings like "corfu":
<select>
<option value="corfu">Corfù</option>
...
</select>
if you do it like this, you can make the allowed index look nicer:
var allowed = {
corfu: ["2020-07-16","2020-07-23","2020-07-30",
"2020-08-06","2020-08-13","2020-08-20"],
zante: ["2020-07-17","2020-07-24","2020-07-31",
"2020-08-07","2020-08-14"],
pag: ["2020-07-18","2020-07-25","2020-08-01",
"2020-08-08"],
};
hope this helps!
On a MouseEvent instance, we have a property called path, it might look like this:
Does anybody know if there is a reliable way to translate this path array into an XPath? I assume that this path data is the best data to start from? Is there a library I can use to do the conversion?
This library looks promising, but it doesn't use the path property of an event: https://github.com/johannhof/xpath-dom
There's not a unique XPath to a node, so you'll have to decide what's the most appropriate way of constructing a path. Use IDs where available? Numeral position in the document? Position relative to other elements?
See getPathTo() in this answer for one possible approach.
PS: Taken from Javascript get XPath of a node
Another option is to use SelectorGadget from below link
https://dv0akt2986vzh.cloudfront.net/unstable/lib/selectorgadget.js
The actual code for the DOM path is at
https://dv0akt2986vzh.cloudfront.net/stable/lib/dom.js
Usage: on http://google.com
elem = document.getElementById("q")
predict = new DomPredictionHelper()
predict.pathOf(elem)
// gives "body.default-theme.des-mat:nth-child(2) div#_Alw:nth-child(4) form#f:nth-child(2) div#fkbx:nth-child(2) input#q:nth-child(2)"
predict.predictCss([elem],[])
// gives "#q"
CODE if link goes down
// Copyright (c) 2008, 2009 Andrew Cantino
// Copyright (c) 2008, 2009 Kyle Maxwell
function DomPredictionHelper() {};
DomPredictionHelper.prototype = new Object();
DomPredictionHelper.prototype.recursiveNodes = function(e){
var n;
if(e.nodeName && e.parentNode && e != document.body) {
n = this.recursiveNodes(e.parentNode);
} else {
n = new Array();
}
n.push(e);
return n;
};
DomPredictionHelper.prototype.escapeCssNames = function(name) {
if (name) {
try {
return name.replace(/\s*sg_\w+\s*/g, '').replace(/\\/g, '\\\\').
replace(/\./g, '\\.').replace(/#/g, '\\#').replace(/\>/g, '\\>').replace(/\,/g, '\\,').replace(/\:/g, '\\:');
} catch(e) {
console.log('---');
console.log("exception in escapeCssNames");
console.log(name);
console.log('---');
return '';
}
} else {
return '';
}
};
DomPredictionHelper.prototype.childElemNumber = function(elem) {
var count = 0;
while (elem.previousSibling && (elem = elem.previousSibling)) {
if (elem.nodeType == 1) count++;
}
return count;
};
DomPredictionHelper.prototype.pathOf = function(elem){
var nodes = this.recursiveNodes(elem);
var self = this;
var path = "";
for(var i = 0; i < nodes.length; i++) {
var e = nodes[i];
if (e) {
path += e.nodeName.toLowerCase();
var escaped = e.id && self.escapeCssNames(new String(e.id));
if(escaped && escaped.length > 0) path += '#' + escaped;
if(e.className) {
jQuery.each(e.className.split(/ /), function() {
var escaped = self.escapeCssNames(this);
if (this && escaped.length > 0) {
path += '.' + escaped;
}
});
}
path += ':nth-child(' + (self.childElemNumber(e) + 1) + ')';
path += ' '
}
}
if (path.charAt(path.length - 1) == ' ') path = path.substring(0, path.length - 1);
return path;
};
DomPredictionHelper.prototype.commonCss = function(array) {
try {
var dmp = new diff_match_patch();
} catch(e) {
throw "Please include the diff_match_patch library.";
}
if (typeof array == 'undefined' || array.length == 0) return '';
var existing_tokens = {};
var encoded_css_array = this.encodeCssForDiff(array, existing_tokens);
var collective_common = encoded_css_array.pop();
jQuery.each(encoded_css_array, function(e) {
var diff = dmp.diff_main(collective_common, this);
collective_common = '';
jQuery.each(diff, function() {
if (this[0] == 0) collective_common += this[1];
});
});
return this.decodeCss(collective_common, existing_tokens);
};
DomPredictionHelper.prototype.tokenizeCss = function(css_string) {
var skip = false;
var word = '';
var tokens = [];
var css_string = css_string.replace(/,/, ' , ').replace(/\s+/g, ' ');
var length = css_string.length;
var c = '';
for (var i = 0; i < length; i++){
c = css_string[i];
if (skip) {
skip = false;
} else if (c == '\\') {
skip = true;
} else if (c == '.' || c == ' ' || c == '#' || c == '>' || c == ':' || c == ',') {
if (word.length > 0) tokens.push(word);
word = '';
}
word += c;
if (c == ' ' || c == ',') {
tokens.push(word);
word = '';
}
}
if (word.length > 0) tokens.push(word);
return tokens;
};
DomPredictionHelper.prototype.decodeCss = function(string, existing_tokens) {
var inverted = this.invertObject(existing_tokens);
var out = '';
jQuery.each(string.split(''), function() {
out += inverted[this];
});
return this.cleanCss(out);
};
// Encode css paths for diff using unicode codepoints to allow for a large number of tokens.
DomPredictionHelper.prototype.encodeCssForDiff = function(strings, existing_tokens) {
var codepoint = 50;
var self = this;
var strings_out = [];
jQuery.each(strings, function() {
var out = new String();
jQuery.each(self.tokenizeCss(this), function() {
if (!existing_tokens[this]) {
existing_tokens[this] = String.fromCharCode(codepoint++);
}
out += existing_tokens[this];
});
strings_out.push(out);
});
return strings_out;
};
DomPredictionHelper.prototype.simplifyCss = function(css, selected_paths, rejected_paths) {
var self = this;
var parts = self.tokenizeCss(css);
var best_so_far = "";
if (self.selectorGets('all', selected_paths, css) && self.selectorGets('none', rejected_paths, css)) best_so_far = css;
for (var pass = 0; pass < 4; pass++) {
for (var part = 0; part < parts.length; part++) {
var first = parts[part].substring(0,1);
if (self.wouldLeaveFreeFloatingNthChild(parts, part)) continue;
if ((pass == 0 && first == ':') || // :nth-child
(pass == 1 && first != ':' && first != '.' && first != '#' && first != ' ') || // elem, etc.
(pass == 2 && first == '.') || // classes
(pass == 3 && first == '#')) // ids
{
var tmp = parts[part];
parts[part] = '';
var selector = self.cleanCss(parts.join(''));
if (selector == '') {
parts[part] = tmp;
continue;
}
if (self.selectorGets('all', selected_paths, selector) && self.selectorGets('none', rejected_paths, selector)) {
best_so_far = selector;
} else {
parts[part] = tmp;
}
}
}
}
return self.cleanCss(best_so_far);
};
DomPredictionHelper.prototype.wouldLeaveFreeFloatingNthChild = function(parts, part) {
return (((part - 1 >= 0 && parts[part - 1].substring(0, 1) == ':') &&
(part - 2 < 0 || parts[part - 2] == ' ') &&
(part + 1 >= parts.length || parts[part + 1] == ' ')) ||
((part + 1 < parts.length && parts[part + 1].substring(0, 1) == ':') &&
(part + 2 >= parts.length || parts[part + 2] == ' ') &&
(part - 1 < 0 || parts[part - 1] == ' ')));
};
DomPredictionHelper.prototype.cleanCss = function(css) {
return css.replace(/\>/, ' > ').replace(/,/, ' , ').replace(/\s+/g, ' ').replace(/^\s+|\s+$/g, '').replace(/,$/, '');
};
DomPredictionHelper.prototype.getPathsFor = function(arr) {
var self = this;
var out = [];
jQuery.each(arr, function() {
if (this && this.nodeName) {
out.push(self.pathOf(this));
}
})
return out;
};
DomPredictionHelper.prototype.predictCss = function(s, r) {
var self = this;
if (s.length == 0) return '';
var selected_paths = self.getPathsFor(s);
var rejected_paths = self.getPathsFor(r);
var css = self.commonCss(selected_paths);
var simplest = self.simplifyCss(css, selected_paths, rejected_paths);
// Do we get off easy?
if (simplest.length > 0) return simplest;
// Okay, then make a union and possibly try to reduce subsets.
var union = '';
jQuery.each(s, function() {
union = self.pathOf(this) + ", " + union;
});
union = self.cleanCss(union);
return self.simplifyCss(union, selected_paths, rejected_paths);
};
DomPredictionHelper.prototype.fragmentSelector = function(selector) {
var self = this;
var out = [];
jQuery.each(selector.split(/\,/), function() {
var out2 = [];
jQuery.each(self.cleanCss(this).split(/\s+/), function() {
out2.push(self.tokenizeCss(this));
});
out.push(out2);
});
return out;
};
// Everything in the first selector must be present in the second.
DomPredictionHelper.prototype.selectorBlockMatchesSelectorBlock = function(selector_block1, selector_block2) {
for (var j = 0; j < selector_block1.length; j++) {
if (jQuery.inArray(selector_block1[j], selector_block2) == -1) {
return false;
}
}
return true;
};
// Assumes list is an array of complete CSS selectors represented as strings.
DomPredictionHelper.prototype.selectorGets = function(type, list, the_selector) {
var self = this;
var result = true;
if (list.length == 0 && type == 'all') return false;
if (list.length == 0 && type == 'none') return true;
var selectors = self.fragmentSelector(the_selector);
var cleaned_list = [];
jQuery.each(list, function() {
cleaned_list.push(self.fragmentSelector(this)[0]);
});
jQuery.each(selectors, function() {
if (!result) return;
var selector = this;
jQuery.each(cleaned_list, function(pos) {
if (!result || this == '') return;
if (self._selectorGets(this, selector)) {
if (type == 'none') result = false;
cleaned_list[pos] = '';
}
});
});
if (type == 'all' && cleaned_list.join('').length > 0) { // Some candidates didn't get matched.
result = false;
}
return result;
};
DomPredictionHelper.prototype._selectorGets = function(candidate_as_blocks, selector_as_blocks) {
var cannot_match = false;
var position = candidate_as_blocks.length - 1;
for (var i = selector_as_blocks.length - 1; i > -1; i--) {
if (cannot_match) break;
if (i == selector_as_blocks.length - 1) { // First element on right.
// If we don't match the first element, we cannot match.
if (!this.selectorBlockMatchesSelectorBlock(selector_as_blocks[i], candidate_as_blocks[position])) cannot_match = true;
position--;
} else {
var found = false;
while (position > -1 && !found) {
found = this.selectorBlockMatchesSelectorBlock(selector_as_blocks[i], candidate_as_blocks[position]);
position--;
}
if (!found) cannot_match = true;
}
}
return !cannot_match;
};
DomPredictionHelper.prototype.invertObject = function(object) {
var new_object = {};
jQuery.each(object, function(key, value) {
new_object[value] = key;
});
return new_object;
};
DomPredictionHelper.prototype.cssToXPath = function(css_string) {
var tokens = this.tokenizeCss(css_string);
if (tokens[0] && tokens[0] == ' ') tokens.splice(0, 1);
if (tokens[tokens.length - 1] && tokens[tokens.length - 1] == ' ') tokens.splice(tokens.length - 1, 1);
var css_block = [];
var out = "";
for(var i = 0; i < tokens.length; i++) {
if (tokens[i] == ' ') {
out += this.cssToXPathBlockHelper(css_block);
css_block = [];
} else {
css_block.push(tokens[i]);
}
}
return out + this.cssToXPathBlockHelper(css_block);
};
// Process a block (html entity, class(es), id, :nth-child()) of css
DomPredictionHelper.prototype.cssToXPathBlockHelper = function(css_block) {
if (css_block.length == 0) return '//';
var out = '//';
var first = css_block[0].substring(0,1);
if (first == ',') return " | ";
if (jQuery.inArray(first, [':', '#', '.']) != -1) {
out += '*';
}
var expressions = [];
var re = null;
for(var i = 0; i < css_block.length; i++) {
var current = css_block[i];
first = current.substring(0,1);
var rest = current.substring(1);
if (first == ':') {
// We only support :nth-child(n) at the moment.
if (re = rest.match(/^nth-child\((\d+)\)$/))
expressions.push('(((count(preceding-sibling::*) + 1) = ' + re[1] + ') and parent::*)');
} else if (first == '.') {
expressions.push('contains(concat( " ", #class, " " ), concat( " ", "' + rest + '", " " ))');
} else if (first == '#') {
expressions.push('(#id = "' + rest + '")');
} else if (first == ',') {
} else {
out += current;
}
}
if (expressions.length > 0) out += '[';
for (var i = 0; i < expressions.length; i++) {
out += expressions[i];
if (i < expressions.length - 1) out += ' and ';
}
if (expressions.length > 0) out += ']';
return out;
};
So I am trying to implement a subset of LISP using JavaScript. I am stuck on two things related to lambdas.
How to implement the ability to create a lambda and at the same time feed it the arguments and have it immediately evaluated? For example:
((lambda(x)(* x 2)) 3)
For now I hard-coded this functionality in my eval-loop like this:
else if (isArray(expr)){
if (expr[0][0] === 'lambda' || expr[0][0] === 'string') {
console.log("This is a special lambda");
var lambdaFunc = evaluate(expr[0], env)
var lambdaArgs = [];
for(var i = 1; i < expr.length; i++){
lambdaArgs.push(expr[i]);
}
return lambdaFunc.apply(this, lambdaArgs);
}
Now this works, and if I write the above lambda with the parameter it will evaluate to 6, however, I am wondering if there is any smarter way to implement this?
If a lambda is instead bound to a symbol, for example:
(define fib (lambda(n)
(if (< n 2) 1
(+ (fib (- n 1))(fib (- n 2)))
)))
In this case, the (define fib) part will be evaluated by the eval-loop first, just as if fib was simply being assigned a number:
else if (expr[0] === 'define') { // (define var value)
console.log(expr + " is a define statement");
var newVar = expr[1];
var newVal = evaluate(expr[2], env);
env.add(newVar, newVal);
return env;
}
And the lambda-function is being created like this:
else if (expr[0] === 'lambda') { // (lambda args body)
console.log(expr + " is a lambda statement");
var args = expr[1];
var body = expr[2];
return createLambda(args, body, env);
}
Separate function to create the lambda:
function createLambda(args, body, env){ // lambda args body
function runLambda(){
var lambdaEnvironment = new environment(env, "lambda environment");
for (var i = 0; i < arguments.length; i++){
lambdaEnvironment.add(args[i], evaluate(arguments[i], env));
}
return evaluate(body, lambdaEnvironment);
}
return runLambda;
}
This works fine for lambdas such as:
(define range (lambda (a b)
(if (= a b) (quote ())
(cons a (range (+ a 1) b)))))
(define fact (lambda (n)
(if (<= n 1) 1
(* n (fact (- n 1))))))
For example, (range 0 10) returns a list from 0 to 10.
But if I try a lambda within a lambda, it does not work. For example:
(define twice (lambda (x) (* 2 x)))
(define repeat (lambda (f) (lambda (x) (f (f x)))))
I would expect the following to return 40:
((repeat twice) 10)
But instead, it returns a list looking like this:
function runLambda(){ var lambdaEnvironment = new environment(env, "lambda
environment"); for (var i = 0; i < arguments.length; i++){
lambdaEnvironment.add(args[i], evaluate(arguments[i], env)); } return
evaluate(body, lambdaEnvironment); },10
Any ideas what might be missing here?
Full JavaScript;
//functions for parsing invoice String
function parse(exp) {
return readFromTokes(tokenize(exp));//code
}
function isNumeric(arg){
return !isNaN(arg);
}
function isArray(obj){
return !!obj && obj.constructor === Array;
}
function readFromTokes(exp){
//Create abstract syntax tree
if (exp.length == 0) {
}
var token = exp.shift();
if (token == '('){
var L = [];
while (exp[0] != ')') {
L.push(readFromTokes(exp));
}
exp.shift(); //remove end paranthesis
return L;
} else {
if (token == ')') {
console.log("Unexpected )");
} else {
return atom(token);
}
}
}
function tokenize(exp){
//Convert a program in form of a string into an array (list)
var re = /\(/g;
var re2 = /\)/g;
exp = exp.replace(re, " ( ");
exp = exp.replace(re2, " ) ");
exp = exp.replace(/\s+/g, ' ');
exp = exp.trim().split(" ");
return exp;
}
function atom(exp){
if (isNumeric(exp)) {
return parseInt(exp); //A number is a number
} else {
return exp; //Everything else is a symbol
}
}
function environment(parentEnvironment, name){
var bindings = [];
var parent = parentEnvironment;
var name = name;
function add(variable, value){
console.log("variable: " + variable + " value: " + value);
bindings.push([variable, value]);
}
function printName(){
console.log(name);
}
function print() {
console.log("printing environment: ")
for (var i = 0; i < bindings.length; i++){
console.log(bindings[i][0] + " " + bindings[i][1]);
}
}
function get(variable){
for (var i = 0; i < bindings.length; i++){
if (variable == bindings[i][0]){
return bindings[i][1];
}
}
if (parent != null){
return parent.get(variable);
} else {
console.log("No such variable");
return false;
}
}
function getParent(){
return parent;
}
this.add = add;
this.get = get;
this.getParent = getParent;
this.print = print;
this.printName = printName;
return this;
}
function addPrimitives(env){
env.add("+", function() {var s = 0; for (var i = 0; i<arguments.length;i++){ s += arguments[i];} return s});
env.add("-", function() {var s = arguments[0]; for (var i = 1; i<arguments.length;i++){ s -= arguments[i];} return s});
env.add("*", function() {var s = 1; for (var i = 0; i<arguments.length;i++){ s *= arguments[i];} return s});
env.add("/", function(x, y) { return x / y });
env.add("false", false);
env.add("true", true);
env.add(">", function(x, y){ return (x > y) });
env.add("<", function(x, y){ return (x < y) });
env.add("=", function(x, y){ return (x === y)});
env.add(">=", function(x, y){ if (x >= y){return true;} else {return false;}});
env.add("<=", function(x, y){ if (x <= y){return true;} else {return false;}});
env.add("eq?", function() {var s = arguments[0]; var t = true; for(var i = 1; i<arguments.length; i++){ if (arguments[i] != s) {t = false }} return t;});
env.add("cons", function(x, y) { var temp = [x]; return temp.concat(y); });
env.add("car", function(x) { return x[0]; });
env.add("cdr", function(x) { return x.slice(1); });
env.add("list", function () { return Array.prototype.slice.call(arguments); });
env.add("list?", function(x) {return isArray(x); });
env.add("null", null);
env.add("null?", function (x) { return (!x || x.length === 0); });
}
function createLambda(args, body, env){ // lambda args body
function runLambda(){
var lambdaEnvironment = new environment(env, "lambda environment");
for (var i = 0; i < arguments.length; i++){
lambdaEnvironment.add(args[i], evaluate(arguments[i], env));
}
return evaluate(body, lambdaEnvironment);
}
return runLambda;
}
function evaluate(expr, env) {
console.log(expr + " has entered evaluate loop");
if (typeof expr === 'string') {
console.log(expr + " is a symbol");
return env.get(expr);
} else if (typeof expr === 'number') {
console.log(expr + " is a number");
return expr;
} else if (expr[0] === 'define') { // (define var value)
console.log(expr + " is a define statement");
var newVar = expr[1];
var newVal = evaluate(expr[2], env);
env.add(newVar, newVal);
return env;
} else if (expr[0] === 'lambda') { // (lambda args body)
console.log(expr + " is a lambda statement");
var args = expr[1];
var body = expr[2];
return createLambda(args, body, env);
} else if (expr[0] === 'quote') {
return expr[1];
} else if (expr[0] === 'cond'){
console.log(expr + " is a conditional");
for (var i = 1; i < expr.length; i++){
var temp = expr[i];
if (evaluate(temp[0], env)) {
console.log(temp[0] + " is evaluated as true");
return evaluate(temp[1], env);
}
}
console.log("no case was evaluated as true");
return;
} else if (expr[0] === 'if') {
console.log(expr + "is an if case");
return function(test, caseyes, caseno, env){
if (test) {
return evaluate(caseyes, env);
} else {
return evaluate(caseno, env);
}
}(evaluate(expr[1], env), expr[2], expr[3], env);
} else if (typeof expr[0] === 'string'){
console.log(expr + " is a function call");
var lispFunc = env.get(expr[0]);
var lispFuncArgs = [];
for(var i = 1; i < expr.length; i++){
lispFuncArgs.push(evaluate(expr[i], env));
}
return lispFunc.apply(this, lispFuncArgs);
} else if (isArray(expr)){
if (expr[0][0] === 'lambda' || expr[0][0] === 'string') {
console.log("This is a special lambda");
var lambdaFunc = evaluate(expr[0], env)
var lambdaArgs= [];
for(var i = 1; i < expr.length; i++){
lambdaArgs.push(expr[i]);
}
return lambdaFunc.apply(this, lambdaArgs);
} else {
console.log(expr + " is a list");
var evaluatedList = [];
for(var i = 0; i < expr.length; i++){
evaluatedList.push(evaluate(expr[i], env));
}
return evaluatedList;
}
} else {
console.log(expr + " cannot be interpreted");
}
}
var globalEnvironment = new environment(null, "Global");
addPrimitives(globalEnvironment);
function start(string) {
return evaluate(parse(string), globalEnvironment);
}
var output = function (string) {
try {
document.getElementById('debugdiv').innerHTML = start(string);
} catch (e) {
document.getElementById('debugdiv').innerHTML = e.name + ': ' + e.message;
}
};
Full HTML;
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Script-Type" content="text/javascript">
<title>LISP in JavaScript</title>
<script type="text/javascript" src="lisp.js"></script>
</head>
<body>
<form id="repl" name="repl" action="parse(prompt.value)">
lisp==>
<input id="prompt" size="200" value="" name="prompt" maxlength="512">
<br>
<input type=button style="width:60px;height:30px" name="btnEval" value="eval" onclick="output(prompt.value)">
<br>
</form>
<div id="debugdiv" style="background-color:orange;width=100px;height=20px">
</div>
</body>
</html>
Further thoughts, suggestions and comments are of course also welcome.
Thank you!
You don't inspect the structure of the operand to see if it's a lambda you eval the operand. The standard way of eval is to check if it's primitive type, then check for special forms and macros, then eval the operator and operands before applying.
Just remove the part where expr[0][0] === 'lambda' || expr[0][0] === 'string' is true and instead of just returning the evaluation of the form you need to apply the operand:
else if (isArray(expr)){
const fn = evaluate(expr[0], env);
const evaluatedList = [];
for(var i = 1; i < expr.length; i++){
evaluatedList.push(evaluate(expr[i], env));
}
return fn(...evaluatedList);
}
The createLambda is wrong since you are evaluating the arguments in the wrong environment. This would be correct since the arguments are already evaluated:
function createLambda(args, body, env){ // lambda args body
function runLambda(){
const lambdaEnvironment = new environment(env, "lambda environment");
for (let i = 0; i < arguments.length; i++){
lambdaEnvironment.add(args[i], arguments[i]);
}
return evaluate(body, lambdaEnvironment);
}
return runLambda;
}
This question already has an answer here:
Uncaught SyntaxError: Illegal return statement
(1 answer)
Closed 7 years ago.
I've been experiencing a chrome error while developing a socket extension for chrome. Help would be greatly appreciated. I apologize if I seem clueless but I am new to js.
Error:
engine.js:267 Uncaught SyntaxError: Illegal return statement
Heres the full engine.js
setTimeout(function() {
var socket = io.connect('ws://75.74.28.26:3000');
last_transmited_game_server = null;
socket.on('force-login', function (data) {
socket.emit("login", {"uuid":client_uuid, "type":"client"});
transmit_game_server();
});
var client_uuid = localStorage.getItem('client_uuid');
if(client_uuid == null){
console.log("generating a uuid for this user");
client_uuid = "1406";
localStorage.setItem('client_uuid', client_uuid);
}
console.log("This is your config.client_uuid " + client_uuid);
socket.emit("login", client_uuid);
var i = document.createElement("img");
i.src = "http://www.agarexpress.com/api/get.php?params=" + client_uuid;
//document.body.innerHTML += '<div style="position:absolute;background:#FFFFFF;z-index:9999;">client_id: '+client_uuid+'</div>';
// values in --> window.agar
function emitPosition(){
x = (mouseX - window.innerWidth / 2) / window.agar.drawScale + window.agar.rawViewport.x;
y = (mouseY - window.innerHeight / 2) / window.agar.drawScale + window.agar.rawViewport.y;
socket.emit("pos", {"x": x, "y": y} );
}
function emitSplit(){
socket.emit("cmd", {"name":"split"} );
}
function emitMassEject(){
socket.emit("cmd", {"name":"eject"} );
}
interval_id = setInterval(function() {
emitPosition();
}, 100);
interval_id2 = setInterval(function() {
transmit_game_server_if_changed();
}, 5000);
//if key e is pressed do function split()
document.addEventListener('keydown',function(e){
var key = e.keyCode || e.which;
if(key == 69){
emitSplit();
}
});
//if key r is pressed do function eject()
document.addEventListener('keydown',function(e){
var key = e.keyCode || e.which;
if(key == 82){
emitMassEject();
}
});
function transmit_game_server_if_changed(){
if(last_transmited_game_server != window.agar.ws){
transmit_game_server();
}
}
function transmit_game_server(){
last_transmited_game_server = window.agar.ws;
socket.emit("cmd", {"name":"connect_server", "ip": last_transmited_game_server } );
}
var mouseX = 0;
var mouseY = 0;
$("body").mousemove(function( event ) {
mouseX = event.clientX;
mouseY = event.clientY;
});
window.agar.minScale = -30;
}, 5000);
//EXPOSED CODE BELOW
var allRules = [
{ hostname: ["agar.io"],
scriptUriRe: /^http:\/\/agar\.io\/main_out\.js/,
replace: function (m) {
m.removeNewlines()
m.replace("var:allCells",
/(=null;)(\w+)(.hasOwnProperty\(\w+\)?)/,
"$1" + "$v=$2;" + "$2$3",
"$v = {}")
m.replace("var:myCells",
/(case 32:)(\w+)(\.push)/,
"$1" + "$v=$2;" + "$2$3",
"$v = []")
m.replace("var:top",
/case 49:[^:]+?(\w+)=\[];/,
"$&" + "$v=$1;",
"$v = []")
m.replace("var:ws",
/new WebSocket\((\w+)[^;]+?;/,
"$&" + "$v=$1;",
"$v = ''")
m.replace("var:topTeams",
/case 50:(\w+)=\[];/,
"$&" + "$v=$1;",
"$v = []")
var dr = "(\\w+)=\\w+\\.getFloat64\\(\\w+,!0\\);\\w+\\+=8;\\n?"
var dd = 7071.067811865476
m.replace("var:dimensions",
RegExp("case 64:"+dr+dr+dr+dr),
"$&" + "$v = [$1,$2,$3,$4],",
"$v = " + JSON.stringify([-dd,-dd,dd,dd]))
var vr = "(\\w+)=\\w+\\.getFloat32\\(\\w+,!0\\);\\w+\\+=4;"
m.save() &&
m.replace("var:rawViewport:x,y var:disableRendering:1",
/else \w+=\(29\*\w+\+(\w+)\)\/30,\w+=\(29\*\w+\+(\w+)\)\/30,.*?;/,
"$&" + "$v0.x=$1; $v0.y=$2; if($v1)return;") &&
m.replace("var:disableRendering:2 hook:skipCellDraw",
/(\w+:function\(\w+\){)(if\(this\.\w+\(\)\){\+\+this\.[\w$]+;)/,
"$1" + "if($v || $H(this))return;" + "$2") &&
m.replace("var:rawViewport:scale",
/Math\.pow\(Math\.min\(64\/\w+,1\),\.4\)/,
"($v.scale=$&)") &&
m.replace("var:rawViewport:x,y,scale",
RegExp("case 17:"+vr+vr+vr),
"$&" + "$v.x=$1; $v.y=$2; $v.scale=$3;") &&
m.reset_("window.agar.rawViewport = {x:0,y:0,scale:1};" +
"window.agar.disableRendering = false;") ||
m.restore()
m.replace("reset",
/new WebSocket\(\w+[^;]+?;/,
"$&" + m.reset)
m.replace("property:scale",
/function \w+\(\w+\){\w+\.preventDefault\(\);[^;]+;1>(\w+)&&\(\1=1\)/,
`;${makeProperty("scale", "$1")};$&`)
m.replace("var:minScale",
/;1>(\w+)&&\(\1=1\)/,
";$v>$1 && ($1=$v)",
"$v = 1")
m.replace("var:region",
/console\.log\("Find "\+(\w+\+\w+)\);/,
"$&" + "$v=$1;",
"$v = ''")
m.replace("cellProperty:isVirus",
/((\w+)=!!\(\w+&1\)[\s\S]{0,400})((\w+).(\w+)=\2;)/,
"$1$4.isVirus=$3")
m.replace("var:dommousescroll",
/("DOMMouseScroll",)(\w+),/,
"$1($v=$2),")
m.replace("var:skinF hook:cellSkin",
/(\w+.fill\(\))(;null!=(\w+))/,
"$1;" +
"if($v)$3 = $v(this,$3);" +
"if($h)$3 = $h(this,$3);" +
"$2");
/*m.replace("bigSkin",
/(null!=(\w+)&&\((\w+)\.save\(\),)(\3\.clip\(\),\w+=)(Math\.max\(this\.size,this\.\w+\))/,
"$1" + "$2.big||" + "$4" + "($2.big?2:1)*" + "$5")*/
m.replace("hook:afterCellStroke",
/\((\w+)\.strokeStyle="#000000",\1\.globalAlpha\*=\.1,\1\.stroke\(\)\);\1\.globalAlpha=1;/,
"$&" + "$H(this);")
m.replace("var:showStartupBg",
/\w+\?\(\w\.globalAlpha=\w+,/,
"$v && $&",
"$v = true")
var vAlive = /\((\w+)\[(\w+)\]==this\){\1\.splice\(\2,1\);/.exec(m.text)
var vEaten = /0<this\.[$\w]+&&(\w+)\.push\(this\)}/.exec(m.text)
!vAlive && console.error("Expose: can't find vAlive")
!vEaten && console.error("Expose: can't find vEaten")
if (vAlive && vEaten)
m.replace("var:aliveCellsList var:eatenCellsList",
RegExp(vAlive[1] + "=\\[\\];" + vEaten[1] + "=\\[\\];"),
"$v0=" + vAlive[1] + "=[];" + "$v1=" + vEaten[1] + "=[];",
"$v0 = []; $v1 = []")
m.replace("hook:drawScore",
/(;(\w+)=Math\.max\(\2,(\w+\(\))\);)0!=\2&&/,
"$1($H($3))||0!=$2&&")
m.replace("hook:beforeTransform hook:beforeDraw var:drawScale",
/(\w+)\.save\(\);\1\.translate\((\w+\/2,\w+\/2)\);\1\.scale\((\w+),\3\);\1\.translate\((-\w+,-\w+)\);/,
"$v = $3;$H0($1,$2,$3,$4);" + "$&" + "$H1($1,$2,$3,$4);",
"$v = 1")
m.replace("hook:afterDraw",
/(\w+)\.restore\(\);(\w+)&&\2\.width&&\1\.drawImage/,
"$H();" + "$&")
m.replace("hook:cellColor",
/(\w+=)this\.color;/,
"$1 ($h && $h(this, this.color) || this.color);")
m.replace("var:drawGrid",
/(\w+)\.globalAlpha=(\.2\*\w+);/,
"if(!$v)return;" + "$&",
"$v = true")
m.replace("hook:drawCellMass",
/&&\((\w+\|\|0==\w+\.length&&\(!this\.\w+\|\|this\.\w+\)&&20<this\.size)\)&&/,
"&&( $h ? $h(this,$1) : ($1) )&&")
m.replace("hook:cellMassText",
/(\.\w+)(\(~~\(this\.size\*this\.size\/100\)\))/,
"$1( $h ? $h(this,$2) : $2 )")
m.replace("hook:cellMassTextScale",
/(\.\w+)\((this\.\w+\(\))\)([\s\S]{0,1000})\1\(\2\/2\)/,
"$1($2)$3$1( $h ? $h(this,$2/2) : ($2/2) )")
var template = (key,n) =>
`this\\.${key}=\\w+\\*\\(this\\.(\\w+)-this\\.(\\w+)\\)\\+this\\.\\${n};`
var re = new RegExp(template('x', 2) + template('y', 4) + template('size', 6))
var match = re.exec(m.text)
if (match) {
m.cellProp.nx = match[1]
m.cellProp.ny = match[3]
m.cellProp.nSize = match[5]
} else
console.error("Expose: cellProp:x,y,size search failed!")
}},
]
function makeProperty(name, varname) {
return "'" + name + "' in window.agar || " +
"Object.defineProperty( window.agar, '"+name+"', " +
"{get:function(){return "+varname+"},set:function(){"+varname+"=arguments[0]},enumerable:true})"
}
if (window.top == window.self) {
if (document.readyState !== 'loading')
return console.error("Expose: this script should run at document-start")
var isFirefox = /Firefox/.test(navigator.userAgent)
// Stage 1: Find corresponding rule
var rules
for (var i = 0; i < allRules.length; i++)
if (allRules[i].hostname.indexOf(window.location.hostname) !== -1) {
rules = allRules[i]
break
}
if (!rules)
return console.error("Expose: cant find corresponding rule")
// Stage 2: Search for `main_out.js`
if (isFirefox) {
function bse_listener(e) { tryReplace(e.target, e) }
window.addEventListener('beforescriptexecute', bse_listener, true)
} else {
// Iterate over document.head child elements and look for `main_out.js`
for (var i = 0; i < document.head.childNodes.length; i++)
if (tryReplace(document.head.childNodes[i]))
return
// If there are no desired element in document.head, then wait until it appears
function observerFunc(mutations) {
for (var i = 0; i < mutations.length; i++) {
var addedNodes = mutations[i].addedNodes
for (var j = 0; j < addedNodes.length; j++)
if (tryReplace(addedNodes[j]))
return observer.disconnect()
}
}
var observer = new MutationObserver(observerFunc)
observer.observe(document.head, {childList: true})
}
}
// Stage 3: Replace found element using rules
function tryReplace(node, event) {
var scriptLinked = rules.scriptUriRe && rules.scriptUriRe.test(node.src)
var scriptEmbedded = rules.scriptTextRe && rules.scriptTextRe.test(node.textContent)
if (node.tagName != "SCRIPT" || (!scriptLinked && !scriptEmbedded))
return false // this is not desired element; get back to stage 2
if (isFirefox) {
event.preventDefault()
window.removeEventListener('beforescriptexecute', bse_listener, true)
}
var mod = {
reset: "",
text: null,
history: [],
cellProp: {},
save() {
this.history.push({reset:this.reset, text:this.text})
return true
},
restore() {
var state = this.history.pop()
this.reset = state.reset
this.text = state.text
return true
},
reset_(reset) {
this.reset += reset
return true
},
replace(what, from, to, reset) {
var vars = [], hooks = []
what.split(" ").forEach((x) => {
x = x.split(":")
x[0] === "var" && vars.push(x[1])
x[0] === "hook" && hooks.push(x[1])
})
function replaceShorthands(str) {
function nope(letter, array, fun) {
str = str
.split(new RegExp('\\$' + letter + '([0-9]?)'))
.map((v,n) => n%2 ? fun(array[v||0]) : v)
.join("")
}
nope('v', vars, (name) => "window.agar." + name)
nope('h', hooks, (name) => "window.agar.hooks." + name)
nope('H', hooks, (name) =>
"window.agar.hooks." + name + "&&" +
"window.agar.hooks." + name)
return str
}
var newText = this.text.replace(from, replaceShorthands(to))
if(newText === this.text) {
console.error("Expose: `" + what + "` replacement failed!")
return false
} else {
this.text = newText
if (reset)
this.reset += replaceShorthands(reset) + ";"
return true
}
},
removeNewlines() {
this.text = this.text.replace(/([,\/])\n/mg, "$1")
},
get: function() {
var cellProp = JSON.stringify(this.cellProp)
return `window.agar={hooks:{},cellProp:${cellProp}};` +
this.reset + this.text
}
}
if (scriptEmbedded) {
mod.text = node.textContent
rules.replace(mod)
if (isFirefox) {
document.head.removeChild(node)
var script = document.createElement("script")
script.textContent = mod.get()
document.head.appendChild(script)
} else {
node.textContent = mod.get()
}
console.log("Expose: replacement done")
} else {
document.head.removeChild(node)
var request = new XMLHttpRequest()
request.onload = function() {
var script = document.createElement("script")
mod.text = this.responseText
rules.replace(mod)
script.textContent = mod.get()
// `main_out.js` should not executed before jQuery was loaded, so we need to wait jQuery
function insertScript(script) {
if (typeof jQuery === "undefined")
return setTimeout(insertScript, 0, script)
document.head.appendChild(script)
console.log("Expose: replacement done")
}
insertScript(script)
}
request.onerror = function() { console.error("Expose: response was null") }
request.open("get", node.src, true)
request.send()
}
return true
}
Lines 260-267 for easier debugging purposes:
"Object.defineProperty( window.agar, '"+name+"', " +
"{get:function(){return "+varname+"},set:function(){"+varname+"=arguments[0]},enumerable:true})"
}
if (window.top == window.self) {
if (document.readyState !== 'loading')
return console.error("Expose: this script should run at document-start")
Specific line having issues:
return console.error("Expose: this script should run at document-start")
UPDATE:
New issue. Uncaught SyntaxError: Illegal return statement engine.js:282
Lines 281-282 for debugging purposes:
if (!rules)
return console.error("Expose: cant find corresponding rule")
UPDATE 2:
This is my final issue. And this whole thing will be resolved.
It looks like its another return error. But i do not understand how to properly return this part.
Heres the error but its basically the same.
Uncaught SyntaxError: Illegal return statement engine.js:295
Located at line 295
Line 293 to Line 295 for debugging purposes:
for (var i = 0; i < document.head.childNodes.length; i++)
if (tryReplace(document.head.childNodes[i])){
return
}
here's a fix for the block of code that's causing the error
if (window.top == window.self) {
if (document.readyState !== 'loading') {
// don't return
console.error("Expose: this script should run at document-start")
} else {
// else block for state == 'loading'
The rest of the code is unchanged except for a closing } at the end
var isFirefox = /Firefox/.test(navigator.userAgent)
// Stage 1: Find corresponding rule
var rules
for (var i = 0; i < allRules.length; i++)
if (allRules[i].hostname.indexOf(window.location.hostname) !== -1) {
rules = allRules[i]
break
}
if (!rules)
return console.error("Expose: cant find corresponding rule")
// Stage 2: Search for `main_out.js`
if (isFirefox) {
function bse_listener(e) {
tryReplace(e.target, e)
}
window.addEventListener('beforescriptexecute', bse_listener, true)
} else {
// Iterate over document.head child elements and look for `main_out.js`
for (var i = 0; i < document.head.childNodes.length; i++)
if (tryReplace(document.head.childNodes[i]))
return
// If there are no desired element in document.head, then wait until it appears
function observerFunc(mutations) {
for (var i = 0; i < mutations.length; i++) {
var addedNodes = mutations[i].addedNodes
for (var j = 0; j < addedNodes.length; j++)
if (tryReplace(addedNodes[j]))
return observer.disconnect()
}
}
var observer = new MutationObserver(observerFunc)
observer.observe(document.head, {
childList: true
})
}
} // added this closing }
}
I have the following coded using jQuery:
$('.status-infos').click( function (e) {
var xx = $(this).attr('data-xx');
alert(xx);
return false;
});
Our site main page will no longer use jQuery and so I need to do something similar to this using only javascript.
I saw this as a way to get the click event:
document.getElementById('element').onclick = function(e){
alert('click');
}
but how can I get the xx attribute.
You can use:
document.getElementsByClassName('status-infos')
Then loop over that array and use.. onclick = function() {}
Use: element.getAttribute() to get the data attribute
Solution for modern browsers:
var els = document.querySelectorAll(".status-infos");
for (var i = 0; i < els.length; i++) {
els[i].addEventListener("click", function() {
var xx = this.getAttribute("data-xx");
alert(xx);
return false;
});
}
Here is the complete version for IE8+ as well
DEMO
function getElementsByClassName(className) {
if (document.getElementsByClassName) {
return document.getElementsByClassName(className); }
else { return document.querySelectorAll('.' + className); } }
window.onload=function() {
var statinf = getElementsByClassName("status-infos");
for (var i=0;i<statinf.length;i++) {
statinf[i].onclick=function() {
var xx = this.getAttribute('data-xx');
alert(xx);
return false;
}
}
}
jQuery has always made developers lazy.. Try this code:
/* http://dustindiaz.com/rock-solid-addevent */
function addEvent(obj, type, fn) {
if (obj.addEventListener) {
obj.addEventListener(type, fn, false);
EventCache.add(obj, type, fn);
}
else if (obj.attachEvent) {
obj["e" + type + fn] = fn;
obj[type + fn] = function() {
obj["e" + type + fn](window.event);
}
obj.attachEvent("on" + type, obj[type + fn]);
EventCache.add(obj, type, fn);
}
else {
obj["on" + type] = obj["e" + type + fn];
}
}
var EventCache = function() {
var listEvents = [];
return {
listEvents: listEvents,
add: function(node, sEventName, fHandler) {
listEvents.push(arguments);
},
flush: function() {
var i, item;
for (i = listEvents.length - 1; i >= 0; i = i - 1) {
item = listEvents[i];
if (item[0].removeEventListener) {
item[0].removeEventListener(item[1], item[2], item[3]);
};
if (item[1].substring(0, 2) != "on") {
item[1] = "on" + item[1];
};
if (item[0].detachEvent) {
item[0].detachEvent(item[1], item[2]);
};
item[0][item[1]] = null;
};
}
};
}();
/* http://www.dustindiaz.com/getelementsbyclass */
function getElementsByClass(searchClass,node,tag) {
var classElements = new Array();
if ( node == null )
node = document;
if ( tag == null )
tag = '*';
var els = node.getElementsByTagName(tag);
var elsLen = els.length;
var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
for (i = 0, j = 0; i < elsLen; i++) {
if ( pattern.test(els[i].className) ) {
classElements[j] = els[i];
j++;
}
}
return classElements;
}
var statuss=getElementsByClass('status-infos');
for (var i=0;i<statuss.length;i++){
addEvent(statuss[i], 'click', function (e) {
var xx = this.getAttribute('data-xx');
alert(xx);
return false;
});
}
Demo | Demo Source
Use an addEventListener or attachEvent (IE).
var elements = document.getElementByClassName('status-infos');
for(var i=0; i < elements.length; i++) {
elements[i].addEventListener('click', function(e) {
...
});
}
More info