Compare Two Arrays

The method below compares two arrays to verify that they are the same.

It is a method, so be sure to place it above or before any code that uses it.

It was written to compare two arrays of

pageRef.marginPreferences.columnsPositions from Adobe InDesign.

Array.prototype.isSameAs = function ( compareTo ) {

//-------------------------------------------------------------------------

//-- I S S A M E A S

//-------------------------------------------------------------------------

//-- Generic: Yes, quite. JavaScript or ExtendScript

//-------------------------------------------------------------------------

//-- Purpose: To compare two arrays to verify that they are the same.

//-------------------------------------------------------------------------

//-- Arguments: The array to compare to. This is a method, it is attached

//-- to the first array.

//-------------------------------------------------------------------------

//-- Calls: Nothing.

//-------------------------------------------------------------------------

//-- Returns: True if the arrays are the same, false otherwise.

//-------------------------------------------------------------------------

//-- Sample Use:

//~ var a1 = [1,2,3] ;

//~ var a2 = [1,2,3] ;

//~ var a3 = [1,2,'3'] ;

//~ var a4 = '[1,2,3]' ;

//~ $.writeln ( a1.isSameAs(a2) ) ;

//~ $.writeln ( a1.isSameAs(a3) ) ;

//~ $.writeln ( a1.isSameAs(a4) ) ;

//-------------------------------------------------------------------------

//-- Notes:

//-- The function expects the elements to exactly match, change

//-- !== to != to allow duck type matches.

//-- This is a method. It must be declared BEFORE / ABOVE any code

//-- that uses it.

//-------------------------------------------------------------------------

//-- Written: 2009.09.22 by Jon S. Winters of electronic publishing support

//-- eps@electronicpublishingsupport.com

//-------------------------------------------------------------------------

//-- Make sure the passed argument is an array.

if ( ! ( ( typeof compareTo == 'object') &&

( compareTo.constructor.toString().match(/array/i) != null ) ) ) {

return false ;

}

//

//-- Make sure the length of both arrays is the same

var masterLength = this.length ;

if ( masterLength != compareTo.length ) {

return false ;

}

//

//-- Now compare every element

for ( var i = masterLength - 1 ; i >= 0 ; i-- ) {

if ( this[i] !== compareTo[i] ) {

return false ;

}

}

//

//-- At this point the arrays must be the same.

return true ;

}