Parent Child Tree Works with nested 'if-else' but not with 'function recursion' in javascript

Question

I have to arrange list of given array in form of a parent child array. I am able to do that with nested if-else statement but am unable to do that with function recursion. Below is the code for working nested if-else method and not-working function recursion method.

Here are the arrays

var arr = [
{"parent": "root",      "name": "one"},
{"parent": "one",       "name": "one one" },
{"parent": "one one",   "name": "one one one"},
{"parent": "one one",   "name": "one one two"},
{"parent": "root",      "name": "two"},
{"parent": "root",      "name": "three"},
{"parent": "root",      "name": "four"},
{"parent": "four",      "name": "four one"},
{"parent": "four one",  "name": "four one one"},
{"parent": "four one",  "name": "four one two"}];

var output111 = { 'parent': "0", 'name': "root", 'folder_list' : [] };
var output222 = { 'parent': "0", 'name': "root", 'folder_list' : [] };

Here is the nested if-else method which works perfectly

function getTreeHardCoded (parent) {

    for ( i = 0; i < arr.length; i++) {
        if( arr[i].parent === parent.name ) {
            var folderListI = {parent : arr[i].parent, name : arr[i].name, folder_list : []};
            parent.folder_list.push(folderListI);

            for ( j = 0; j < arr.length; j++) {
                if( arr[j].parent === arr[i].name ) {
                    var folderListJ = { parent: arr[j].parent, name: arr[j].name, folder_list:[]};
                    folderListI.folder_list.push(folderListJ);

                    for ( k = 0; k < arr.length; k++) {
                        if( arr[k].parent === arr[j].name ) {
                            var folderListK = { parent : arr[k].parent, name : arr[k].name, folder_list : [] };
                            folderListJ.folder_list.push(folderListK);

                        }
                    }
                }
            }
        }
    }
}
getTreeHardCoded(output111);

Here is function recursion method which do not work

function getTree (parent) {

    for ( i = 0; i < arr.length; i++) { 

        if( arr[i].parent === parent.name ) {

            var folderList = {
                parent : arr[i].parent,
                name : arr[i].name,
                folder_list : []
            };

            parent.folder_list.push(folderList);

            getTree(folderList);

        }
    }
}

getTree(output222);

Here is the FIDDLE with complete code, having desired output in white bg and output with function recursion in gray bg.

Thanks in advance..

Andy Gaskell · Accepted Answer · 2016-02-13 06:18:31Z

2

Talk about globals biting you in the ass! Put a var in front of all of your index variables (i, j, and k).

answered Feb 13, 2016 at 6:18

Andy Gaskell

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2 Comments

kanudo Over a year ago

amazing, thats it... such a silly mistake... idiot me... never thought that not defining the var in for-loop can also create problem

Andy Gaskell Over a year ago

No, not idiot. It happens to all of us and sometimes all you need is a code review. Make sure you understand why it happened and keep on going :)

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