How to convert an array to a tree?

Question

I have two arrays

["a", "b", "c"] ["a", "b", "d"] 

I want to convert it to

 { a : { b : { c : null, d : null } } } 

How can i do this?

Answer 1

 var tree = {} function addToTree(tree, array) { for (var i = 0, length = array.length; i < length; i++) { tree = tree[array[i]] = tree[array[i]] || {} } } addToTree(tree, ["a", "b", "c"]) addToTree(tree, ["a", "b", "d"]) /*{ "a": { "b": { "c": {}, "d": {} } } }*/ 

The only thing he does not do is set the leaves of the tree to zero - he sets them to an empty object. This is normal?

If you want the leaves to be empty, use the following instead:

 function addToTree(tree, array) { for (var i = 0, length = array.length; i < length; i++) { tree = tree[array[i]] = ((i == length - 1) ? null : tree[array[i]] || {}) } } // or, without the i == length - 1 check in each iteration: function addToTree(tree, array) { for (var i = 0, length = array.length; i < length -1; i++) { tree = tree[array[i]] = tree[array[i]] || {}; } tree[array[i]] = null; } /*{ "a": { "b": { "c": null, "d": null } } }*/