Merging objects (associative arrays)

Question

What’s the best/standard way of merging two associative arrays in JavaScript? Does everyone just do it by rolling their own for loop?

Answer 1

jquery has a boolean for deep copy. You could do something like that:

MergeRecursive = function(arr1, arr2){
    $.extend(true, arr1, arr2);
    return arr1;                
};

Also you can edit this function to support n-arrays to merge.

ArrayMergeRecursive = function(){
     if(arguments.length < 2){
          throw new Error("ArrayMergeRecursive: Please enter two or more objects to merge!");
     }

    var arr1=arguments[0];
    for(var i=0; i<=arguments.length; i++ ){
        $.extend(true, arr1, arguments[i]);                 
    }

    return arr1;                
};

So now you can do

var arr1 = {'color': {'mycolor': 'red'}, 3: 5},
    arr2 = {4: 10, 'color': {'favorite': 'green', 0: 'blue'}},
    arr3 = ['Peter','Jhon','Demosthenes'],
    results = ArrayMergeRecursive(arr1, arr2, arr3); // (arr1, arr2 ... arrN)
console.log("Result is:", results);