How to convert JS Object to Array

Question

I need to convert a hash map

{ 
    \"fruit\" : [\"mango\",\"orange\"],
    \"veg\"   : [\"carrot\"]
} 

to

[ 
  { \"type\         


        

Answer 1

In a browser that supports ES5 – or where you added a shim for it:

var stuff = { 
    "fruit" : ["mango","orange"],
    "veg"   : ["carrot"]
}

var array = Object.keys(stuff).map(function(key) {
    return {"type" : key, "name" : stuff[key] }
})

See: Object.keys, Array's map

Or, in the old fashion way:

var stuff = { 
    "fruit" : ["mango","orange"],
    "veg"   : ["carrot"]
}

var array = []

for (var key in stuff) {
    if (stuff.hasOwnProperty(key)) {
        array.push({"type" : key, "name" : stuff[key] })
    }
}

Please notice that in both cases the array's value are shared because in JS the objects are passed by reference. So, for instance, stuff["fruit"] and array[0].name points to the same reference of the array ["mango", "orange"]. It means, if you change one of them, the other will be changed as well:

stuff["fruit"].push("apple");
alert(array[0].name); // "mango", "orange", "apple"

To avoid that, you can use slice to have a one-level deep copy of your array. So in the code above, instead of:

"name" : stuff[key]

you will have:

"name" : stuff[key].slice(0)

Hope it helps.

Answer 2

You can do it like this (in a working snippet):

var input = { 
    "fruit" : ["mango","orange"],
    "veg"   : ["carrot"]
} 

var output = [], item;

for (var type in input) {
    item = {};
    item.type = type;
    item.name = input[type];
    output.push(item);
}

// display result
document.write(JSON.stringify(output));

---

Or, if you or someone else has been extending the Object prototype with enumerable properties (which I think is a bad practice personally), then you could use this to protect from that:

var input = { 
    "fruit" : ["mango","orange"],
    "veg"   : ["carrot"]
} 

var output = [], item;

for (var type in input) {
    if (input.hasOwnProperty(type)) {
        item = {};
        item.type = type;
        item.name = input[type];
        output.push(item);
    }
}

// display result
document.write(JSON.stringify(output));

---

And, using some more modern functionality:

var input = { 
    "fruit" : ["mango","orange"],
    "veg"   : ["carrot"]
};

var output = Object.keys(input).map(function(key) {
   return {type: key, name: input[key]};
});

// display the result
document.write(JSON.stringify(output));