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Empty an Array

This is one of the fastest and easiest ways of emptying an array. Of course there are may other ways, but those usually include creation of a new array. This way you reuse the same array.

var myArray = ["one", "two", "three"];

// console.log( myArray ) => ["one", "two", "three"]

myArray.length = 0;

// console.log( myArray ) => []

Comments

  1. ng87
    Permalink to comment#

    isnt:

    myArray = [];

    just as good?

    • Salman Abbas
      Permalink to comment#

      Not if you have references to the array lying around..

  2. CaTaHaC
    Permalink to comment#

    I bet this:
    myArray.length = 0;
    does not work in all browsers where the snippet provided above – does.

  3. Permalink to comment#

    Excellent code, myArray.empty() works as well.

    • Tem Corner
      Permalink to comment#

      it’s not a standard prototype on the Array constructor.
      Atleast not in the latest WebKit browsers.

    • erick
      Permalink to comment#

      not really-doesnt work in some browsers
      myArray=[]; is excellent

  4. Genzeb
    Permalink to comment#

    Ha, just do:
    arrayobj.splice(0,arrayobj.length).

    You can even add that to a prototype as

    Array.prototype.empty() {this.splice(0,this.length);}

    and you are done.

  5. Permalink to comment#

    I think:

    myArray = [];
    /* or */
    myArray = new Array();

    Would be the best, since it’s cross-browser stuff.

    • Maxx
      Permalink to comment#

      Make sure you understand what that really means. Your are creating a NEW INSTANCE, and not using the same array. This can lead to a lot of fun debugging if you are not aware of that in cases where references to the original array exist.

    • Avi Algaly
      Permalink to comment#

      yet again if you have reference then its lost

  6. Matt W
    Permalink to comment#

    The problem with myArray = [] and myArray = new Array() is that technically you are not emptying the array, but instead you are creating a new array. Creating new arrays is a bit of work for browsers, so simply setting the array’s length to 0 is probably best.

  7. Nisse

    none of the examples works

    • zenoob

      Out of the above I’ve only tested emptying an array through splicing and it did work perfectly.

  8. Permalink to comment#

    Old thread but here are my two cents:

    As the above jsPerf test case shows, creating a new array is FASTER than setting length to 0. The reason for this is that most of the built-in functions and constructors for JS nowadays tend to use native code under the surface to optimize (thanks in no small part to Javascript becoming so popular). This is at least the case in Chrome although I can’t vouch for other browsers.

    In short stick to creating new arrays – old tricks like this aren’t really necessary any more.

    • Karl
      Permalink to comment#

      Once again you are missing the point. Creating a new array breaks any references to said array.

  9. Permalink to comment#

    P.S. Splicing is the worst by far: http://jsperf.com/emptying-arrays/4

  10. Phani

    Still there is a flaw in both of your methods.
    A simple example is try with
    var a = [“one”,”two”,”three”];
    a = [];
    a = new Array();
    var a = [“four”,”five”,”six”];
    a.join(‘*’);
    console.log(a); // Now we expect the out as four*five*six.
    But, output will be ***four*five*six. Which is never a correct procedure. I am looking for a perfect solution, which works on all browsers. Please, let me know if any one of you have one.

    • Kevin
      Permalink to comment#

      I know it has been over a year since your post, but that snippet worked as expected in Internet Explorer 8 and Firefox 21.

  11. This solution works best for me

    var sounds = new Array(“a”,”b”,”c”);

    for(var m=0; m<sounds.length; m++){
        sounds.pop();
    }
    

    //returns an empty array

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