I have a sample code:
function getKeyword() {
var instance = this;
var googlePattern = /(www\.google\..*)/;
this.params = function(parameters) {
var result = [];
var params = parameters.split("&");
for(var p in params) {
var kv = params[p].split("=");
result[kv[0]] = kv[1];
}
return result;
};
this.googleKeywords = function(params){
var query = params["q"];
var pattern = /"(.*?)"|(\w+)/g;
return decodeURIComponent(query).replace(/\+/g, " ").match(pattern);
};
this.parseReferrer = function(){
var result = [];
var pathAndParams = document.referrer.split("?");
if(pathAndParams.length == 2) {
var path = pathAndParams[0];
var params = this.params(pathAndParams[1]);
if(path.search(googlePattern) > 0) {
result = this.googleKeywords(params);
}
}
return result;
};
return this.parseReferrer();
}
And then:
<script type="text/javascript">
if (document.referrer && document.referrer != "") {
if (document.referrer.search(/google\.*/i) != -1){
var keyword = getKeyword();
alert(keyword);
} else {
alert('Not search from google');
}
} else {
alert('Not referrer');
}
</script>
Ex: when i search with keyword is "iphone 5", result not show alert("iphone 5") ? How to fix it ?
The JavaScript for in construct loops over more than just the entries in the array. If you want to use for in you need to make sure that you're only processing the actual parameters. This is easiest accomplished by checking for hasOwnProperty:
this.params = function(parameters) {
var result = [];
var params = parameters.split("&");
for(var p in params) {
if (params.hasOwnProperty(p))
{
var kv = params[p].split("=");
result[kv[0]] = kv[1];
}
}
return result;
};
Alternatively you can use a regular for loop over the array:
this.params = function(parameters) {
var result = [];
var params = parameters.split("&");
for(var i=0; i < params.length; i++) {
var kv = params[i].split("=");
result[kv[0]] = kv[1];
}
return result;
};
Related
I'm working through Cracking the Coding Interview and I thought I'd implement all the data structures in JS 5. Can anyone explain to me why my toString method isn't working?
Thanks!
function Node(data) {
this.next = null;
this.data = data;
}
Node.prototype.appendToTail = function(data) {
var end = new Node(data);
var n = this;
while (n.next != null) {
n = n.next;
}
n.next = end;
}
Node.prototype.toString = function(head) {
console.log(head)
if (head == null) {
return ""
} else {
return head.data.toString() + "-> " + head.next.toString();
}
}
var ll = new Node(1);
ll.appendToTail(3);
ll.appendToTail(4);
console.log(ll.toString())
function Node(data) {
this.next = null;
this.data = data;
}
Node.prototype.appendToTail = function(data) {
var end = new Node(data);
var n = this;
while (n.next != null) {
n = n.next;
}
n.next = end;
};
Node.prototype.toString = function() {
var returnValue = String(this.data);
if (this.next) {
returnValue = returnValue + "-> " + String(this.next);
}
return returnValue;
};
var ll = new Node(1);
ll.appendToTail(3);
ll.appendToTail(4);
console.log(String(ll))
or avoid this kind of problems completly and do not use prototype, class, this, call, etc
Your toString function takes an argument, but you're not passing it when you call toString.
If you want to access the node, you should use this, instead of passing in a value
Node.prototype.toString = function() {
var result = this.data.toString();
if (this.next) {
result += "-> " + this.next.toString();
}
return result;
}
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)
}
}
}
I am trying to push elements to an array in a nested loop, but only the last item is getting repeated in the final array, where am I going wrong, very new to javascript asynchronous concept.Below is the function in which I push the items to an array.
$scope.showBeList = function(feed) {
if (feed[srcServ.KEY_CONTENT_TEXT]) {
var content = JSON.parse(feed[srcServ.KEY_CONTENT_TEXT])
if (content) {
$scope.beList = {};
for (var key in content) {
var decorationVal;
//reading value from a lokijs collection
var decoration = dataServ[srcServ.CONST_COLLECTION_DECORATION].find({
'name': key
});
if (decoration && decoration.length) {
decorationVal = decoration[0];
if (decorationVal != null) {
var tempObj = JSON.parse(decorationVal.value);
if (tempObj) {
var header = tempObj[key][key + '_HEADER'];
if (header) {
var counter = content[key].length;
var tempItems = [];
for (var j = 0; j < content[key].length; j++) {
(function(j) {
var obj = {};
obj[srcServ.KEY_MAIN_HEADER] = tempObj[key][srcServ.KEY_DESC];
obj[srcServ.KEY_SUB_HEADER] = header[srcServ.KEY_DESC];
obj.id = j;
var itemVal = content[key][j][key + '_HEADER'];
var details = [];
var notes = [];
for (var item in itemVal) {
var val = null;
var found = false;
for (var i = 0; i < header.field.length; i++) {
if (header.field[i].name == item) {
val = header.field[i];
found = true;
break;
}
}
if (found && val != null) {
val[srcServ.KEY_DESC_VALUE] = itemVal[item];
details.push(val);
}
}
obj.details = details;
counter--;
if (counter == 0) {
$scope.showMoreDetails = true;
$scope.beList.beItems = tempItems;
console.log(JSON.stringify($scope.beList));
}
tempItems.push(obj)
})(j);
// $scope.beList.beItems.push(obj);
}
}
}
}
}
}
}
}
}
I have an array like this:
var myObjArray = [{city: 'milwaukee', state: 'wi'},
{city:'madison', state: 'wi'},
{city:'greenbay', state: 'wi'},
{city:'madison', state: 'wi'}];
How would I compare the array against itself to find duplicates.
(Note: I need to keep the duplicates, so maybe I could add a property to the object as a flag).
How about something like:
var bucket = {};
for(var i=0;i<array.length;i++) {
var item = array[i];
var hash = JSON.stringify(item); //or some a hashing algorithm...
var prev = bucket[hash];
if(prev) {
prev.duplicate = item.duplicate = true;
} else {
bucket[hash] = item
}
}
Or same without dependending upon JSON.stringify:
var markDuplicates = function(array, hashFunc) {
var bucket = {};
for(var i=0;i<array.length;i++) {
var item = array[i];
var hash = hashFunc(item);
var prev = bucket[hash];
if(prev) {
prev.duplicate = item.duplicate = true;
} else {
bucket[hash] = item
}
}
return array;
};
markDuplicates(yourArray, function(item) { return item.city + item.state; });
I am currently doing this but it isn't working:
var tempArray=new Array();
var number = 15;
tempArray[number]='blabla';
for (var key in tempArray) {
alert(tempArray[key]);
}
the output that I get is:
in_array function (element) { var retur = false; for (var values in this) { if (this[values] == element) { retur = true; break; } } return retur; }
What am I doing wrong?
In JavaScript we use Objects.
var obj = {};
obj["15"] = "blabla";
obj.fifteen = "blablah";
for(var i in obj) {
alert(obj[i]);
}