Array comparison in plain JavaScript

Comparing two arrays in JavaScript :

Array.prototype.isEqualTo = function ( compareTo ) {
 if ( this.length !== compareTo.length ) return false;
 for ( var i = 0; i < this.length; i ++ ){
 if ( this[i] !== compareTo[i] ) return false;
 }
 return true;
}

#array

#javascript

Written by Arne Fostvedt

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mlb

With a few performance improvements :

Array.prototype.isEqualTo = function (compareTo) {
 var self = this // cache array
 , length = self.length // cache length
 if(length != compareTo.length) return false // compare numbers, strict equalty isn't necessary
 for(;length--;) if(self[length] !== compareTo[length]) return false // decrement is faster with for loops
 return true
}

over 1 year ago ·