Is JavaScript's array.clear() not a function?

Question

I'm trying to empty an array containing my drawn coordinates when a button "clear" is pressed.

When I call drawnDivs.clear(), I get an error that it is not a function. drawnDivs is certainly an array, and I have Firebug console.logs printing things out. It's hosted here.

Out of interest, where did you get the idea to use clear()? It doesn't appear to be a part of Javascript. — thomasrutter, Oct 26 '10 at 03:55
a google search got me here: http://www.roseindia.net/java/javascript-array/javascript-array-clear.shtml — Nona Urbiz, Oct 26 '10 at 04:20

score 81 · Accepted Answer · answered Oct 26 '10 at 03:50

81

Nope, it's not. But drawnDivs.length = 0 should work.

answered Oct 26 '10 at 03:50

jordanbtucker

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This will work if it's a true array, and not just an array-like object. – thomasrutter Oct 26 '10 at 03:54
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@thomasrutter. True but it will preserve references and any other addition properties and functions defined on the array. – jordanbtucker Oct 26 '10 at 04:13
yes, this is still the best solution overall. And to be honest, it would still work on array-like objects, it just wouldn't free any of the existing members from memory right away. So only a minor point really. – thomasrutter Oct 26 '10 at 12:43
@thomasrutter -an "arraylike" object, is not an Array, to begin with - so...(?!) . – Bekim Bacaj Nov 10 '16 at 05:59
Objects that can be used as if they are arrays but which aren't arrays are fairly common in JavaScript. If you want your array handing code to work with "real" arrays as well as objects which can act as arrays, then you have to make sure it can cope with the latter. – thomasrutter Nov 11 '16 at 12:34

score 9 · Answer 2 · answered Oct 26 '10 at 03:52

9

drawnDivs = [];

answered Oct 26 '10 at 03:52

Mike Ruhlin

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Be careful, since this will not modify other references to the object. – Josh Lee Oct 26 '10 at 03:59

score 4 · Answer 3 · edited May 23 '17 at 12:02

4

It was answered in Stack Overflow question How do I empty an array in JavaScript?.

Two examples from the answer:

var A = ['some', 'values', 'here'];

//Method 1

//(This was my original answer to the question)

A = [];




// Method 2 (as suggested by Matthew Crumley)

A.length = 0

And here is a nice write up on these two methods by Dr. Axel Rauschmayer.

edited May 23 '17 at 12:02

Community

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answered Oct 26 '10 at 04:06

subhaze

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The chosen answer in the referred link is not the right solution as it does not clear the variables that refer to the array being cleared. The correct answer in that thread is http://stackoverflow.com/a/8134354/206687 – Shamasis Bhattacharya Sep 26 '12 at 13:04

score 2 · Answer 4 · edited Nov 11 '15 at 19:46

2

An optimized way to do it is:

while (arr.pop()) {}

See http://jsperf.com/kbk-clear-array/2.

edited Nov 11 '15 at 19:46

Peter Mortensen

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answered Feb 04 '14 at 16:17

user3271659

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This fails if the array has empty slots. This should do it: `while (arr.length > 0) { arr.pop(); }` – Geoff May 21 '15 at 13:55
**No, this should be:** ` while(arr.length){ arr.pop(); }` – Jorge Rivera Dec 10 '15 at 15:47

score 0 · Answer 5 · edited Nov 10 '15 at 04:23

0

You could alternately use the Prototype library and then, use Prototype's clear() method.

edited Nov 10 '15 at 04:23

Anik Islam Abhi

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answered Sep 23 '12 at 17:44

Debosmit Ray

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Could be an alternative way, but i think there are a lot of easier ways without the use of libraries to clear an array. – Ruben-J Sep 23 '12 at 19:41
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Yea -- that would work, but it is using a sledgehammer to kill a fly. – Jeremy J Starcher Sep 23 '12 at 20:16

Is JavaScript's array.clear() not a function?

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