Loops are a type of control flow structure in programming in which a series of statements may be executed repeatedly until some condition is met.
162
votes
10answers
19k views
Javascript closure inside loops - simple practical example
Closures are one of those things which has been discussed a lot on SO, but this situation pops up a lot for me and I'm always left scratching my head what to do.
var funcs = {};
for (var i = 0; i ...
20
votes
5answers
4k views
Access outside variable in loop from Javascript closure
See:
for (var i in this.items) {
var item = this.items[i];
$("#showcasenav").append("<li id=\"showcasebutton_"+item.id+"\"><img src=\"/images/showcase/icon-"+item.id+".png\" ...
24
votes
7answers
4k views
Doesn't JavaScript support closures with local variables?
I am very puzzled about this code:
var closures = [];
function create() {
for (var i = 0; i < 5; i++) {
closures[i] = function() {
alert("i = " + i);
};
}
}
function run() {
...
12
votes
1answer
7k views
Event handlers inside a Javascript loop - need a closure?
I'm working with a bit of html and Javascript code that I've taken over from someone else. The page reloads a table of data (via an asynchronous request) every ten seconds, and then re-builds the ...
33
votes
6answers
10k views
Speed up the loop operation in R
i have a big performance problem in R. I wrote a function that iterates over an data.frame object. It simply adds a new col to a data.frame and accumulate sth. (simple operation). The data.frame has ...
85
votes
17answers
33k views
Difference between declaring variables before or in loop?
I have always wondered if, in general, declaring a throw-away variable before a loop, as opposed to repeatedly inside the loop, makes any (performance) difference?
A (quite pointless example) in ...
16
votes
3answers
9k views
How does a function in a loop (which returns another function) work?
I've been trying to assign a function to onclick event of a dynamically created "a" tag in JavaScript. All of the tags are created in a loop as follows:
for ( var i = 0; i < 4; i++ )
{
var a = ...
6
votes
5answers
2k views
Please explain the use of JavaScript closures in loops [duplicate]
Possible Duplicate:
Javascript closure inside loops - simple practical example
I have read a number of explanations about closures and closures inside loops. I have a hard time ...
147
votes
12answers
54k views
Calling remove in foreach loop in Java
In Java, is it legal to call remove on a collection when iterating through the collection using a foreach loop? For instance:
List<String> names = ....
for (String name : names) {
// Do ...
94
votes
8answers
128k views
How to iterate over a JSON structure?
I have the following JSON structure:
[ {"id":"10", "class": "child-of-9"}, {"id":"11", "classd": "child-of-10"}];
how to iterate over it using jquery or javascript?
392
votes
3answers
52k views
How foreach actually works
Let me prefix this by saying that I know what foreach is, does and how to use it. This question concerns how it works under the bonnet, and I don't want any answers along the lines of "this is how you ...
63
votes
33answers
13k views
JavaScript - Are loops really faster in reverse…?
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 ...
51
votes
5answers
29k views
do { … } while (0) what is it good for? [duplicate]
Possible Duplicate:
Why are there sometimes meaningless do/while and if/else statements in C/C++ macros?
I've been seeing that expression for over 10 years now. I've been trying to think ...
72
votes
8answers
5k views
Optimizing away a “while(1);” in C++0x
Updated, see below!
I have heard and read that C++0x allows an compiler to print "Hello" for the following snippet
#include <iostream>
int main() {
while(1)
;
std::cout << ...
42
votes
11answers
15k views
Is there any overhead to declaring a variable within a loop? (C++)
I am just wondering if there would be any loss of speed or efficiency if you did something like this:
int i = 0;
while(i < 100)
{
int var = 4;
i++;
}
which declares int var one hundred ...
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