473,372 Members | 1,033 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,372 software developers and data experts.

for vs. while which is faster?

8,658 Expert Mod 8TB
out of curiosity, does anyone know, if a for-loop or a while-loop executes faster?

Expand|Select|Wrap|Line Numbers
  1. var elements = document.getElementsByName("name");
  3. for (var i = 0, l = elements.length; i < l; i++)
  4. {
  5.     // some code with elements[i]
  6. }
  8. var elem, i = 0;
  9. while (elem = elements[i])
  10. {
  11.     // some code with elem
  12.     i++;
  13. }
Apr 8 '09 #1
3 3165
428 256MB
while (elem = elements[i]) may not mean what you thought.
Expand|Select|Wrap|Line Numbers
  1. var elements= document.getElementsByName("name"), 
  2. L= elements.length;
  3. while(L){
  4.     elem= elements[--L];
  5.     //do something
  6. }
Apr 8 '09 #2
8,658 Expert Mod 8TB
why should I not mean it like that? I've tested the code (works) and I can be sure the element really exists. furthermore, I don't have to access the array/HTMLCollection in the loop.

I could even go as far as (works too)
Expand|Select|Wrap|Line Numbers
  1. while (elem = elements[i++]) {}
Apr 8 '09 #3
428 256MB
It depends on what you are doing with the elements.

Nodelists are live- if you start with the last element, and count down in the while loop, you can remove some of them safely. If you increment by one and remove an element, you'll skip the next one. Counting down is safer with nodelists.
Apr 9 '09 #4

Sign in to post your reply or Sign up for a free account.

Similar topics

by: Armin Rigo | last post by:
Hi! This is a rant against the optimization trend of the Python interpreter. Sorting a list of 100000 integers in random order takes: * 0.75 seconds in Python 2.1 * 0.51 seconds in Python...
by: YinTat | last post by:
Hi, I learned C++ recently and I made a string class. A code example is this: class CString { public: inline CString(const char *rhs) { m_size = strlen(rhs);
by: jrefactors | last post by:
I heard people saying prefix increment is faster than postfix incerement, but I don't know what's the difference. They both are i = i+1. i++ ++i Please advise. thanks!!
by: Skybuck Flying | last post by:
Hi, I needed a method to determine if a point was on a line segment in 2D. So I googled for some help and so far I have evaluated two methods. The first method was only a formula, the second...
by: James dean | last post by:
I done a test and i really do not know the reason why a jagged array who has the same number of elements as a multidimensional array is faster here is my test. I assign a value and do a small...
by: VenuGopal | last post by:
Hi, why n++ executes faster than n+1..... or does it realli execute faster? thanks Venugopal.B
by: ctman770 | last post by:
Hi Everyone, Is it faster to save the precise location of an html dom node into a variable in js, or to use getElementById everytime you need to access the node? I want to make my application...
by: karthikbalaguru | last post by:
Hi, How is 'Int' Faster than 'Char' ? I think , 'Char' is small and so it should be easily & efficiently . Can someone here provide some info regarding this. Thanks and Regards, Karthik...
by: Python Maniac | last post by:
I am new to Python however I would like some feedback from those who know more about Python than I do at this time. def scrambleLine(line): s = '' for c in line: s += chr(ord(c) | 0x80)...
by: c | last post by:
Hi every one, Me and my Cousin were talking about C and C#, I love C and he loves C#..and were talking C is ...blah blah...C# is Blah Blah ...etc and then we decided to write a program that...
by: CloudSolutions | last post by:
Introduction: For many beginners and individual users, requiring a credit card and email registration may pose a barrier when starting to use cloud servers. However, some cloud server providers now...
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 3 Apr 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome former...
by: taylorcarr | last post by:
A Canon printer is a smart device known for being advanced, efficient, and reliable. It is designed for home, office, and hybrid workspace use and can also be used for a variety of purposes. However,...
by: aa123db | last post by:
Variable and constants Use var or let for variables and const fror constants. Var foo ='bar'; Let foo ='bar';const baz ='bar'; Functions function $name$ ($parameters$) { } ...
by: ryjfgjl | last post by:
If we have dozens or hundreds of excel to import into the database, if we use the excel import function provided by database editors such as navicat, it will be extremely tedious and time-consuming...
by: emmanuelkatto | last post by:
Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud. Please let me know. Thanks! Emmanuel
by: BarryA | last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
by: nemocccc | last post by:
hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?
by: Sonnysonu | last post by:
This is the data of csv file 1 2 3 1 2 3 1 2 3 1 2 3 2 3 2 3 3 the lengths should be different i have to store the data by column-wise with in the specific length. suppose the i have to...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.