I've been told not to use for...in with arrays in JavaScript. Why not?...

In Java you can use a for loop to traverse objects in an array as follows:  String[] myStringArray = {"Hello", "World"}; for (String s : myStringArray) {     // Do something }   Can you do the same in JavaScript?...

This question already has an answer here:                           JavaScript closure inside loops – simple practical example                                      43 answers                                     I am running an event loop of th...

I have the following code:  for(var i = 0; i < list.length; i++){     mc_cli.get(list[i], function(err, response) {         do_something(i);     }); }   mc_cli is a connection to a memcached database. As you can imagine, the callback function is...

I've heard this quite a few times. Are JavaScript loops really faster when counting backward? If so, why? I've seen a few test suite examples showing that reversed loops are quicker, but I can't find any explanation as to why!  I'm...

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Just a quick question about the scoping of JavaScript variables.  Why does the alert() function print the value of i instead of returning undefined?  $(document).ready(function () {     for(var i = 0; i < 10; i += 1){     }       alert("What...

I have code like the following:  function test(obj) {      if(//some conditon) {         obj.onload();     }else{         obj.onerror();     } }   for(var i=0;i<4;i++){         test({         onload:function(e){                       //some code t...

I want to generate each number between 0 to 4 randomly using javascript and each number can appear only once. So I wrote the code:  for(var l=0; l<5; l++) {     var randomNumber = Math.floor(Math.random()*5);       alert(randomNumber) }   but this...

I was reading airbnb javascript guide. There is a particular statement, that says:     Don’t use iterators. Prefer JavaScript’s higher-order functions instead of loops like for-in or for-of.   The reason they give for the above statement is:...