We Keep Coding

Extend Javascript Syntax to Add Typing

I'd like to extend javascript to add custom type checking.
e.g.
function test(welcome:string, num:integer:non-zero) {
console.log(welcome + num)
}
which would compile into:
function test(welcome, num) {
if(Object.prototype.toString.call(welcome) !== "[object String]") {
throw new Error('welcome must be a string')
}
if (!Number.isInteger(num)) {
throw new Error('num must be an integer')
}
console.log(welcome + num)
}
What's the most straightforward way of doing this?
So far i've looked at:
sweet.js (online documentation looks out of date as I think it's going through some sort of internal rewrite)
esprima and escodegen (not sure where to start)
manually parsing using regular expressons

After evaluating all the various options, using sweet.js appears to be the best solution. It's still fairly difficult to get working (and I am probably doing stuff the wrong way) but just in case someone want's to do something similar this here was my solution.
'use strict'
syntax function = function(ctx) {
let funcName = ctx.next().value;
let funcParams = ctx.next().value;
let funcBody = ctx.next().value;
//produce the normal params array
var normalParams = produceNormalParams(funcParams)
//produce the checks
var paramChecks = produceParamChecks(funcParams)
//produce the original funcBody code
//put them together as the final result
var params = ctx.contextify(funcParams)
var paramsArray = []
for (let stx of params) {
paramsArray.push(stx)
}
var inner = #``
var innerStuff = ctx.contextify(funcBody)
for (let item of innerStuff) {
inner = inner.concat(#`${item}`)
}
var result = #`function ${funcName} ${normalParams} {
${paramChecks}
${inner}
}`
return result
function extractParamsAndParamChecks(paramsToken) {
var paramsContext = ctx.contextify(paramsToken)
//extracts the actual parameters
var paramsArray = []
var i = 0;
var firstItembyComma = true
for (let paramItem of paramsContext) {
if (firstItembyComma) {
paramsArray.push({
param: paramItem,
checks: []
})
firstItembyComma = false
}
if (paramItem.value.token.value === ',') {
firstItembyComma = true
i++
} else {
paramsArray[i].checks.push(paramItem.value.token.value)
}
}
for (var i = 0; i < paramsArray.length; i++) {
var checks = paramsArray[i].checks.join('').split(':')
checks.splice(0, 1)
paramsArray[i].checks = checks
}
return paramsArray
}
function produceNormalParams(paramsToken) {
var paramsArray = extractParamsAndParamChecks(paramsToken)
//Produces the final params #string
var inner = #``
var first = true
for (let item of paramsArray) {
if (first === true) {
inner = inner.concat(#`${item.param}`)
} else {
inner = inner.concat(#`,${item.param}`)
}
}
return #`(${inner})`
}
function produceParamChecks(paramsToken) {
var paramsArray = extractParamsAndParamChecks(paramsToken)
var result = #``
for (let paramObject of paramsArray) {
var tests = produceChecks(paramObject)
result = result.concat(#`${tests}`)
}
return result
}
function produceChecks(paramObject) {
var paramToken = paramObject.param
var itemType = paramObject.checks[0]
var checks = paramObject.checks
if (itemType === undefined) return #``
if (itemType === 'array') {
return #`if (Object.prototype.toString.call(${paramToken}) !== "[object Array]") throw new Error('Must be array:' + ${paramToken})`
else {
throw new Error('item type not recognised: ' + itemType)
}
}
}

How to pass a RegEx backreferences as a variable?

I'm trying to pass the backreferences to a dynamically-created-function as a variable (so i could check if the backreferences is set and if not throw an error) but i can't find a solution for passing it. How can you make it work???
This is the code:
class regexMap {
constructor(map) {
this.map = map;
}
replace(str){
for (var i = 0; i < this.map.length; i++){
var regexp = new RegExp(this.map[i][0], 'ig');
str = str.replace(regexp, this.map[i][1].apply(this));
}
return str;
}
}
// EXAMPLE:
var map = [
[/FIND (.*)/g,function(){
var br = '$1'; // Don't work.
if(br != '' && br != undefined){
return 'find(\'$1\');'
} else {
console.error('Find requires a string');
return;
}
}],
];
console.log(new regexMap(map).replace("FIND This is a string\nFIND "));
Thanks!

The fucntion you pass into replace will receive the full match as its first argument and then additional arguments containing the contents of capture groups. So you can declare those in your function, then use the function directly in your regexMap#replace method. See *** comments:
class regexMap {
constructor(map) {
this.map = map;
}
replace(str){
for (var i = 0; i < this.map.length; i++){
var regexp = new RegExp(this.map[i][0], 'ig');
str = str.replace(regexp, this.map[i][1].bind(this)); // ***
}
return str;
}
}
// EXAMPLE:
var map = [
[/FIND (.*)/g,function(m, br){ // ***
if(br != '' && br != undefined){
return 'find(\'' + br + '\');'
} else {
console.error('Find requires a string');
return;
}
}],
];
console.log(new regexMap(map).replace("FIND This is a string\nFIND "));

es6 code broken in es5

I have been trying to translate my code from es6 to es5 because of some framework restrictions at my work... Although I have been quite struggling to locate what the problem is. For some reason the code does not work quite the same, and there is no errors either ...
Can someone tell me If I have translated properly ?
This is the ES6 code :
function filterFunction(items, filters, stringFields = ['Title', 'Description'], angular = false) {
// Filter by the keys of the filters parameter
const filterKeys = Object.keys(filters);
// Set up a mutable filtered object with items
let filtered;
// Angular doesn't like deep clones... *sigh*
if (angular) {
filtered = items;
} else {
filtered = _.cloneDeep(items);
}
// For each key in the supplied filters
for (let key of filterKeys) {
if (key !== 'TextInput') {
filtered = filtered.filter(item => {
// Make sure we have something to filter by...
if (filters[key].length !== 0) {
return _.intersection(filters[key], item[key]).length >= 1;
}
return true;
});
}
// If we're at TextInput, handle things differently
else if (key === 'TextInput') {
filtered = filtered.filter(item => {
let searchString = "";
// For each field specified in the strings array, build a string to search through
for (let field of stringFields) {
// Handle arrays differently
if (!Array.isArray(item[field])) {
searchString += `${item[field]} `.toLowerCase();
} else {
searchString += item[field].join(' ').toLowerCase();
}
}
// Return the item if the string matches our input
return searchString.indexOf(filters[key].toLowerCase()) !== -1;
});
}
}
return filtered;
}
And this is the code I translated that partially 99% work ..
function filterFunction(items, filters, stringFields, angular) {
// Filter by the keys of the filters parameter
var filterKeys = Object.keys(filters);
// Set up a mutable filtered object with items
var filtered;
// Angular doesn't like deep clones... *sigh*
if (angular) {
filtered = items;
} else {
filtered = _.cloneDeep(items);
}
// For each key in the supplied filters
for (var key = 0 ; key < filterKeys.length ; key ++) {
if (filterKeys[key] !== 'TextInput') {
filtered = filtered.filter( function(item) {
// Make sure we have something to filter by...
if (filters[filterKeys[key]].length !== 0) {
return _.intersection(filters[filterKeys[key]], item[filterKeys[key]]).length >= 1;
}
return true;
});
}
// If we're at TextInput, handle things differently
else if (filterKeys[key] === 'TextInput') {
filtered = filtered.filter(function(item) {
var searchString = "";
// For each field specified in the strings array, build a string to search through
for (var field = 0; field < stringFields.length; field ++) {
// Handle arrays differently
console.log(field);
if (!Array.isArray(item[stringFields[field]])) {
searchString += item[stringFields[field]] + ' '.toLowerCase();
} else {
searchString += item[stringFields[field]].join(' ').toLowerCase();
}
}
// Return the item if the string matches our input
return searchString.indexOf(filters[filterKeys[key]].toLowerCase()) !== -1;
});
}
}
return filtered;
}

These two lines
searchString += `${item[field]} `.toLowerCase();
searchString += item[stringFields[field]] + ' '.toLowerCase();
are not equivalent indeed. To apply the toLowerCase method on all parts of the string, you'll need to wrap the ES5 concatenation in parenthesis:
searchString += (item[stringFields[field]] + ' ').toLowerCase();
or, as blanks cannot be lowercased anyway, just use
searchString += item[stringFields[field]].toLowerCase() + ' ';

Here is a translated code from babeljs itself, as commented above.
'use strict';
function filterFunction(items, filters) {
var stringFields = arguments.length <= 2 || arguments[2] === undefined ? ['Title', 'Description'] : arguments[2];
var angular = arguments.length <= 3 || arguments[3] === undefined ? false : arguments[3];
// Filter by the keys of the filters parameter
var filterKeys = Object.keys(filters);
// Set up a mutable filtered object with items
var filtered = void 0;
// Angular doesn't like deep clones... *sigh*
if (angular) {
filtered = items;
} else {
filtered = _.cloneDeep(items);
}
// For each key in the supplied filters
var _iteratorNormalCompletion = true;
var _didIteratorError = false;
var _iteratorError = undefined;
try {
var _loop = function _loop() {
var key = _step.value;
if (key !== 'TextInput') {
filtered = filtered.filter(function (item) {
// Make sure we have something to filter by...
if (filters[key].length !== 0) {
return _.intersection(filters[key], item[key]).length >= 1;
}
return true;
});
}
// If we're at TextInput, handle things differently
else if (key === 'TextInput') {
filtered = filtered.filter(function (item) {
var searchString = "";
// For each field specified in the strings array, build a string to search through
var _iteratorNormalCompletion2 = true;
var _didIteratorError2 = false;
var _iteratorError2 = undefined;
try {
for (var _iterator2 = stringFields[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
var field = _step2.value;
// Handle arrays differently
if (!Array.isArray(item[field])) {
searchString += (item[field] + ' ').toLowerCase();
} else {
searchString += item[field].join(' ').toLowerCase();
}
}
// Return the item if the string matches our input
} catch (err) {
_didIteratorError2 = true;
_iteratorError2 = err;
} finally {
try {
if (!_iteratorNormalCompletion2 && _iterator2.return) {
_iterator2.return();
}
} finally {
if (_didIteratorError2) {
throw _iteratorError2;
}
}
}
return searchString.indexOf(filters[key].toLowerCase()) !== -1;
});
}
};
for (var _iterator = filterKeys[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
_loop();
}
} catch (err) {
_didIteratorError = true;
_iteratorError = err;
} finally {
try {
if (!_iteratorNormalCompletion && _iterator.return) {
_iterator.return();
}
} finally {
if (_didIteratorError) {
throw _iteratorError;
}
}
}
return filtered;
}
p.s. Or there is a better way to use babeljs directly without manually converting it.

javascript remove item from array, if an item already existing in array

following adds items to array:
var arrayOptions = [];
function AddToFilterOptionList(mode) {
arrayOptions.push(mode);
}
remove item from array:
function RemoveFromFilterOptionList(mode) {
var index = arrayOptions.indexOf(mode);
if (index !== -1) {
arrayOptions.splice(index, 1);
}}
for example if i call
AddToFilterOptionList('APPLE') - APPLE should be added to array.
If i again call
AddToFilterOptionList('APPLE+FRUIT') - it should remove the the item 'APPLE' from array arrayOptions and should add APPLE+FRUIT
Any time only one word that starts with APPLE can be in array.
How to find the word like 'APPLE' in javascript.
I tried with Match() which returns the matching word. IndexOf() returns 1 only if whole word is match but not start of word.

Cycle through the Array and then use the startsWith method.
void AddToFilterOptionList(String mode) {
for (i=0; i<arrayOptions.length; i++) {
if (mode.startsWith(arrayOptions[i] == 1)) {
array[i] = mode;
return; // found, so return
}
}
arrayOptions.push(mode); // should only get here if string did not exist.
}

You need to split by + characted and then loop over produced array to add/remove all items:
var arrayOptions = [];
function AddToFilterOptionList(mode) {
mode.split(/\+/g).forEach(function(el) {
var index = arrayOptions.indexOf(el);
if (index !== -1) {
arrayOptions.splice(index, 1);
}
else {
arrayOptions.push(el);
}
});
}
function RemoveFromFilterOptionList(mode) {
var index = arrayOptions.indexOf(mode);
if (index !== -1) {
arrayOptions.splice(index, 1);
}
}
AddToFilterOptionList('APPLE');
document.write('<p>' + arrayOptions); // expect: APPLE
AddToFilterOptionList('APPLE+FRUIT');
document.write('<p>' + arrayOptions); // expect: FRUIT
AddToFilterOptionList('APPLE+FRUIT+CARROT');
document.write('<p>' + arrayOptions); // expect: APPLE,CARROT

This will work assuming the 'this+that' pattern is consistent, and that we only care about the starting item.
http://jsbin.com/gefasuqinu/1/edit?js,console
var arr = [];
function remove(item) {
var f = item.split('+')[0];
for (var i = 0, e = arr.length; i < e; i++) {
if (arr[i].split('+')[0] === f) {
arr.splice(i, 1);
break;
}
}
}
function add(item) {
remove(item);
arr.push(item);
}

UPDATE:
function add (array, fruits) {
var firstFruit = fruits.split('+')[0]
var secondFruit = fruits.split('+')[1]
var found = false
var output = []
output = array.map(function (item) {
if (item.indexOf(firstFruit) > -1) {
found = true
return fruits
}
else return item
})
if (! found) {
array.push(fruits)
}
return output
}
var fruits = []
add(fruits, 'APPLE')
fruits = add(fruits, 'APPLE+GRAPE')
console.log(fruits[0]) // 'APPLE+GRAPE'
fruits = add(fruits, 'APPLE')
console.log(fruits[0]) // 'APPLE'

Try this, the code is not optimised though :P
<html>
<head>
<script src = "jquery-1.10.2.min.js"></script>
<script type = "text/javascript">
var itemList = [];
function addItem()
{
var item = $('#item').val();
if(item != '' || item != 'undefined')
{
if(itemList.length == 0)
itemList.push(item);
else
{
for(i=0;i<itemList.length;i++)
{
var splittedInputItems = [];
splittedInputItems = item.split("+");
var splittedListItems = [];
splittedListItems = itemList[i].split("+");
if(splittedListItems[0] == splittedInputItems[0])
{
itemList.splice(i,1);
itemList.push(item);
return;
}
}
itemList.push(item);
}
}
}
</script>
</head>
<body>
<input id="item" type = "text"/>
<input type = "button" value="Add" onclick="addItem()">
</body>
</html>

let items = [1, 2, 3, 2, 4, 5, 2, 7];
let item = 2;
for (let i = 0; i < items.length; i++) {
if (items[i] === item) {
items.splice(i, 1);
i = i - 1;
}
}
If you want to remove the element '2' from items array, it is a way.

How can I check a string of words to see if they are an anagram of one word

I am trying to figure out a javascript function that will help resolve this test. I need to be able to determine if the string of words (var matches) that is given is an anagram of the word that I am running through (var subject). In this case there would not be a match. Any and all help will be greatly appreciated. Thank you in advance!
var anagram = require('./anagram');
describe('Anagram', function() {
it("no matches",function() {
var subject = anagram("diaper");
var matches = subject.matches([ "hello", "world", "zombies", "pants"]);
expect(matches).toEqual([]);
});
});
This is what I have so far:
for (var i = 0; i < matches.length; i++) {
if (subject.length != matches[i].length) {
return false
} else if (subject.length == matches[i].length){
var anagram = function(subject, matches) {
return subject.split("").sort("").join("") === matches[i].split("").sort("").join("");
};
}

Here is the fiddle:
http://jsfiddle.net/hn8r4v3u/2/
I alphabetized the letters within the word, as you were doing, in a function.
function getAlphaSortedWord(word) {
var baseWordCharArray = word.split("");
baseWordCharArray.sort();
return baseWordCharArray.join("");
}
The code has a set up:
var baseWord = getAlphaSortedWord("bob");
var thingsToCheck = ["obb", "2", "bob", "", "bo", "ob"];
And then solves it two ways, once with filter and once without it.
var matches = _.filter(thingsToCheck, function (str) {
return (baseWord === getAlphaSortedWord(str));
});
var matches2 = [];
for (index = 0; index < thingsToCheck.length; index++) {
if (baseWord === getAlphaSortedWord(thingsToCheck[index])) {
matches2.push(thingsToCheck[index]);
}
}
You should be able to use these to tie in with your real data for the test to pass.
NOTE, I would add some sanity for "is string" to my function if this is going to be production code.

Found here and it works: https://gist.github.com/AlbertoElias/10005056
function areAnagrams(a, b) {
var c = false;
if (a.length !== b.length) {
return c;
}
var hashMap = {};
var char;
var i;
for (i=0;i<a.length;i++) {
char = a[i];
hashMap[char] = hashMap[char] !== undefined ? hashMap[char]+1 : 1;
}
for (i=0;i<b.length;i++) {
char = b[i];
if (hashMap[char] !== undefined) {
if (hashMap[char] > 1) {
hashMap[char]--;
} else {
delete hashMap[char];
}
} else {
return c;
}
}
if (Object.keys(hashMap).length === 0) c = true;
return c;
}