56
votes
30
answers
2.2K
views
JavaScript closure inside loops – simple practical example
var funcs = []; // let's create 3 functions for (var i = 0; i < 3; i++) { // and store them in f
57
votes
30
answers
2K
views
Detecting an undefined object property
What's the best way of checking if an object property in JavaScript is undefined?
57
votes
30
answers
2.6K
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How can I upload files asynchronously with jQuery?
I would like to upload a file asynchronously with jQuery. $(document).ready(function () { $("#uploa
56
votes
30
answers
2.3K
views
How can I change an element's class with JavaScript?
How can I change the class of an HTML element in response to an onclick or any other events using JavaScript?
50
votes
30
answers
1.9K
views
How can I check if an object is an array?
I'm trying to write a function that either accepts a list of strings, or a single string. If it's a
51
votes
14
answers
2.7K
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event.preventDefault() vs. return false
When I want to prevent other event handlers from executing after a certain event is fired, I can use one of tw
63
votes
30
answers
1K
views
How do I loop through or enumerate a JavaScript object?
I have a JavaScript object like the following: var p = { "p1": "value1", "p2": "value2", "p3": "v
51
votes
25
answers
3.1K
views
What is the difference between call and apply?
What is the difference between using call and apply to invoke a function? var func = function() { alert(&ap
54
votes
25
answers
1.6K
views
Get the current URL with JavaScript?
All I want is to get the website URL. Not the URL as taken from a link. On the page loading I need to be able
71
votes
30
answers
2.9K
views
How to round to at most 2 decimal places, if necessary?
I'd like to round at most 2 decimal places, but only if necessary. Input: 10 1.7777777 9.1 Output: 1
52
votes
30
answers
1.1K
views
How can I check for an empty/undefined/null string in JavaScript?
I saw this question, but I didn't see a JavaScript specific example. Is there a simple string.Empty avail
60
votes
30
answers
598
views
Sort array of objects by string property value
I have an array of JavaScript objects: var objs = [ { first_nom: 'Lazslo', last_nom: 'Jam
53
votes
30
answers
1.5K
views
How do I correctly clone a JavaScript object?
I have an object x. I'd like to copy it as object y, such that changes to y do not modify x. I realized t
59
votes
25
answers
3K
views
Checking if a key exists in a JavaScript object?
How do I check if a particular key exists in a JavaScript object or array? If a key doesn't exist, and I
56
votes
20
answers
1.7K
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How to insert an item into an array at a specific index (JavaScript)
I am looking for a JavaScript array insert method, in the style of: arr.insert(index, item) Preferably in jQu
58
votes
30
answers
409
views
Loop through an array in JavaScript
In Java you can use a for loop to traverse objects in an array as follows: String[] myStringArray = {"Hello",
61
votes
30
answers
1.9K
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What is the !! (not not) operator in JavaScript?
I saw some code that seems to use an operator I don't recognize, in the form of two exclamation points, l
59
votes
30
answers
2.4K
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How do I copy to the clipboard in JavaScript?
What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(tex
65
votes
30
answers
1.1K
views
How do I test for an empty JavaScript object?
After an AJAX request, sometimes my application may return an empty object, like: var a = {}; How can I che
61
votes
30
answers
1.2K
views
Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?
The following are two methods of building a link that has the sole purpose of running JavaScript code. Which i
