How to create a nested object given an array of keys
Given is an array like this:
var level = ["a", "b", "x"];
The output should be:
{
"a": {
"b": {
"x": {
}
}
}
}
I tried this:
var level = ["a", "b", "x"];
var o = {};
for (var c = 0, len = level.length; c < len; c +=1 ) {
var part = level[c];
o[part] = {}; // how to remember the last part?
}
How can I remember the last part and add the next level?
You can use reduceRight method by passing an arrow function as argument.
var level = ["a", "b", "x"];
let result = level.reduceRight((obj, elem) => ({[elem]: obj}), {});
console.log(result);Simplest tweak would be to reassign o on each iteration:
var level = ["a", "b", "x"];
var o = {};
var initialO = o;
for (var c = 0, len = level.length; c < len; c +=1 ) {
var part = level[c];
o[part] = {};
o = o[part];
}
console.log(initialO);This might be a clearer way of doing it, though:
const level = ["a", "b", "x"];
const result = {};
level.reduce((accum, key) => {
accum[key] = {};
return accum[key];
}, result);
console.log(result);You might use a check if the level exist and assign only an object if not set.
function addLevels(levels, object) {
levels.reduce((o, l) => o[l] = o[l] || {}, object);
}
var object = {};
addLevels(["a", "b", "x"], object);
addLevels(["a", "d", "z"], object);
console.log(object);This one, I think is easiest if you write it in a functional style.
var level = ["a", "b", "x"];
var o = {};
level.reduce(function (obj, key) {
o[key] = {};
return o[key];
}, o);
Or with a recursive function
const level = ["a", "b", "x"];
const f = (i) => i === level.length ? {} : {[level[i]]: f(i+1)};
console.log(f(0));
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