Merge keys array and values array into an object in Javascript
-
12-09-2019 - |
Question
I have:
var keys = [ "height", "width" ];
var values = [ "12px", "24px" ];
And I'd like to convert it into this object:
{ height: "12px", width: "24px" }
In Python, there's the simple idiom dict(zip(keys,values))
. Is there something similar in jQuery or plain Javascript, or do I have to do this the long way?
Solution
Simple JS function would be:
function toObject(names, values) {
var result = {};
for (var i = 0; i < names.length; i++)
result[names[i]] = values[i];
return result;
}
Of course you could also actually implement functions like zip, etc as JS supports higher order types which make these functional-language-isms easy :D
OTHER TIPS
The simplest ES6 one-liner solution using Array reduce
:
const keys = ['height', 'width'];
const values = ['12px', '24px'];
const merged = keys.reduce((obj, key, index) => ({ ...obj, [key]: values[index] }), {});
As an alternate solution, not already mentioned I think :
var result = {};
keys.forEach((key, idx) => result[key] = values[idx]);
A functional approach with immutability in mind:
const zipObj = xs => ys => xs.reduce( (obj, x, i) => ({ ...obj, [x]: ys[i] }), {})
const arr1 = ['a', 'b', 'c', 'd']
const arr2 = ['e', 'f', 'g', 'h']
const obj = zipObj (arr1) (arr2)
console.log (obj)
You could use a reduce()
function to map the key-value pairs to an object.
/**
* Apply to an existing or new object, parallel arrays of key-value pairs.
*
* @param {string[]} keys - List of keys corresponding to their accociated values.
* @param {object[]} vals - List of values corresponding to their accociated keys.
* @param {object} [ref={}] - Optional reference to an existing object to apply to.
*
* @returns {object} - The modified or new object with the new key-value pairs applied.
*/
function toObject(keys, vals, ref) {
return keys.length === vals.length ? keys.reduce(function(obj, key, index) {
obj[key] = vals[index];
return obj;
}, ref || {}) : null;
}
var keys = [ "height" , "width" ];
var values = [ "12px" , "24px" ];
document.body.innerHTML = '<pre>' + JSON.stringify(toObject(keys, values), null, 2) + '</pre>';
function combineObject( keys, values)
{
var obj = {};
if ( keys.length != values.length)
return null;
for (var index in keys)
obj[keys[index]] = values[index];
return obj;
};
var your_obj = combine( your_keys, your_values);
In the jQuery-Utils project, the ArrayUtils module has a zip function implemented.
//...
zip: function(object, object2, iterator) {
var output = [];
var iterator = iterator || dummy;
$.each(object, function(idx, i){
if (object2[idx]) { output.push([i, object2[idx]]); }
});
return output;
}
//...
You can combine two arrays with map
method, then convert it with Object.fromEntries
.
var keys = ["height", "width"];
var values = ["12px", "24px"];
var array = keys.map(function(el, i) {
return [keys[i], values[i]];
});
// → [["height", "12px"], ["width", "24px"]]
var output = Object.fromEntries(array);
// → {height: "12px", width: "24px"}
console.log(output);