Javascript finding value in recursive array

Question

I made a function in order to find an element in a tree object. My function works, but sometimes the function don't find the value and stop before looking all the tree.

I can't explain why it works sometimes and sometimes not.

Here is my fiddle : http://jsfiddle.net/3cdwA/2/

When you click on categories like "Sciences" you can see that it works. But if you click on "Bandes-Dessinées" it should display "Comics" but it doesn't.

Here is my recursive function :

function getChildrenFromCurrentFolder(tree, targetFolder) {
console.log(tree);
// Find recursivly all direct children of targeted folder
if (targetFolder == tree.id) {
   return tree.folders;
} else if (tree.folders.length > 0) {
   var folders = [];
   for (i = 0; folders.length == 0 && i < tree.folders.length; i++) {
      folders = getChildrenFromCurrentFolder(tree.folders[i], targetFolder);
   }
   return folders;
}
return [];

}

here is my test tree :

tree = {
   'id': 1,
   'name': 'Mes Bookmarks',
   'folders': [
      {
         'id': 2,
         'name': 'Sciences',
         'folders': [
            {
                'id': 3,
                'name': 'Biologie',
                'folders': [
                   {
                      'id': 12,
                      'name': 'Neurologie',
                      'folders': []
                   }
                ]
            },
            {
                'id': 4,
                'name': 'Astrophysique',
                'folders': [
                   {
                      'id': 8,
                      'name': 'Cosmologie',
                      'folders': [
                         {
                            'id': 10,
                            'name': 'Système solaire',
                            'folders': []
                         }
                      ]
                   },
                   {
                      'id': 9,
                      'name': 'Trous noirs',
                      'folders': []
                   }
                ]
            },
            {
                'id': 5,
                'name': 'Mathématiques',
                'folders': []
            }
         ]
      },
      {
         'id': 6,
         'name': 'Actualités',
         'folders': [
            {
                'id': 11,
                'name': 'Monde',
                'folders': []
            }
         ]
      },
      {
         'id': 7,
         'name': 'Bandes-dessinées',
         'folders': [
            {
                'id': 13,
                'name': 'Comics',
                'folders': []
            }
         ]
      }
   ]
};

elclanrs · Accepted Answer · 2014-02-14 10:55:11Z

1

It's a simple, but common mistake. You forgot to declare your loop variables and that's trouble when doing recursion as you're creating a global that's being reused:

function displayFolders() {
    ...
       for (var i = folders.length-1; i >= 0; i--)
    ...    --^--
}

function getChildrenFromCurrentFolder(tree, targetFolder) {
    ...
       for (var i = 0; folders.length == 0 && i < tree.folders.length; i++) {
    ...    --^--
}

function getBreadcrumb(tree, targetFolder, breadcrumb) {
    ...
    for (var i = 0; i < tree['folders'].length; i++)
    ... --^--
}

I'm not sure all the other logic is correct, but this definitely changes the behavior.

http://jsfiddle.net/3cdwA/4/

answered Feb 14, 2014 at 10:55

elclanrs

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2 Comments

KmeCnin Over a year ago

Absolutly ! Thanks alot.

elclanrs Over a year ago

:)There are tools to prevent these issues. Try jshint.com and use "use strict", it should throw an error.

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