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July 21, 2009

Better array search

Update: Added more data to show differences.

During the journey of finding a better linear array search function in javascript, I decided to write my own. I decided to take a different approach. Here’s the outcome.

Array.prototype.small_search = function(search) {
    if (this[0] === search){ return 0; }
    var s = '\x00';
    var a = this.join(s);
    var b = a.search(search)-1;
    return a.substring(0, b).split(s).length;
};

With an array of less than 150 elements, it is much faster than Dustin Diaz’s in_array function. While they aren’t the same, his can be adapted to return the index also.

The only downside with my function is that it becomes much slower after the array length is larger than 150 elements. So, if you have a small array, go ahead and use this, otherwise use Dustin’s.

Times


Array Length: 5
small_search: 0.020ms
in_array:     0.098ms

Array Length: 10
small_search: 0.024ms
in_array:     0.084ms

Array Length: 50
small_search: 0.042ms
in_array:     0.095ms

Array Length: 100
small_search: 0.069ms
in_array:     0.106ms

Array Length: 150
small_search: 0.087ms
in_array:     0.111ms

Array Length: 300
small_search: 0.203ms
in_array:     0.137ms

Array Length: 500
small_search: 0.418ms
in_array:     0.132ms

Array Length: 1000
small_search: 0.813ms
in_array:     0.138ms

Array Length: 5000
small_search: 3.530ms
in_array:     0.312ms

Array Length: 10000
small_search: 6.718ms
in_array:     0.441ms

Test it out on your own and come back with results.