JavaScript associative array to JSON

JavascriptJsonAssociative Array

Javascript Problem Overview


How can I convert a JavaScript associative array into JSON?

I have tried the following:

var AssocArray = new Array();

AssocArray["a"] = "The letter A"

console.log("a = " + AssocArray["a"]);

// result: "a = The letter A"

JSON.stringify(AssocArray);

// result: "[]"

Javascript Solutions


Solution 1 - Javascript

Arrays should only have entries with numerical keys (arrays are also objects but you really should not mix these).

If you convert an array to JSON, the process will only take numerical properties into account. Other properties are simply ignored and that's why you get an empty array as result. Maybe this more obvious if you look at the length of the array:

> AssocArray.length
0

What is often referred to as "associative array" is actually just an object in JS:

var AssocArray = {};  // <- initialize an object, not an array
AssocArray["a"] = "The letter A"

console.log("a = " + AssocArray["a"]); // "a = The letter A"
JSON.stringify(AssocArray); // "{"a":"The letter A"}"

Properties of objects can be accessed via array notation or dot notation (if the key is not a reserved keyword). Thus AssocArray.a is the same as AssocArray['a'].

Solution 2 - Javascript

There are no associative arrays in JavaScript. However, there are objects with named properties, so just don't initialise your "array" with new Array, then it becomes a generic object.

Solution 3 - Javascript

Agreed that it is probably best practice to keep Objects as objects and Arrays as arrays. However, if you have an Object with named properties that you are treating as an array, here is how it can be done:

let tempArr = [];
Object.keys(objectArr).forEach( (element) => {
    tempArr.push(objectArr[element]);
});

let json = JSON.stringify(tempArr);

Solution 4 - Javascript

I posted a fix for this here

You can use this function to modify JSON.stringify to encode arrays, just post it near the beginning of your script (check the link above for more detail):

// Upgrade for JSON.stringify, updated to allow arrays
(function(){
    // Convert array to object
    var convArrToObj = function(array){
        var thisEleObj = new Object();
        if(typeof array == "object"){
            for(var i in array){
                var thisEle = convArrToObj(array[i]);
                thisEleObj[i] = thisEle;
            }
        }else {
            thisEleObj = array;
        }
        return thisEleObj;
    };
    var oldJSONStringify = JSON.stringify;
    JSON.stringify = function(input){
        if(oldJSONStringify(input) == '[]')
            return oldJSONStringify(convArrToObj(input));
        else
            return oldJSONStringify(input);
    };
})();

Solution 5 - Javascript

You might want to push the object into the array

enter code here

var AssocArray = new Array();

AssocArray.push( "The letter A");

console.log("a = " + AssocArray[0]);

// result: "a = The letter A"

console.log( AssocArray[0]);

JSON.stringify(AssocArray);

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionActionOwlView Question on Stackoverflow
Solution 1 - JavascriptFelix KlingView Answer on Stackoverflow
Solution 2 - JavascriptAndreKRView Answer on Stackoverflow
Solution 3 - Javascriptkiller_kohlrabiView Answer on Stackoverflow
Solution 4 - JavascriptJVE999View Answer on Stackoverflow
Solution 5 - JavascriptYene MulatuView Answer on Stackoverflow