Question

I have a javascript array which defines an infinite tree like this.

z=['~GROUPHEAD 0~',
    'Intro',
    'Summary',
    ['~GROUPHEAD 1~',
        'Do this',
        ['~GROUPHEAD 2~',
            'Task 1',
            'Task 2'
        ]
    ]
]

Now
z[0]='~GROUPHEAD 0~';
z[1]='Intro';
z[2]='Summary';
z[3][0]='~GROUPHEAD 1~';
z[3][1]='Do this';
z[3][2][0]='~GROUPHEAD 2~';
z[3][2][1]='Task 1';
z[3][2][2]='Task 2';
z...[0] is a Header

Problem

I want to send a number say 322 or 3.2.2 or [3][2][2] to select ‘Task 2’ (i.e. z[3][2][2])
Can anyone help; also is there a better way to do this?

Edit

I need to call it 100s of time

Answer 1

you can either split the number and recursively look it up:

var path = '3.2.2',
    root = z;

var item = (function walk( root, path ){
    root = root[ path.shift() ];
    return path.length ? walk( root, path ) : root;
})( root, path.split('.') );

Or you can do something like:

var path = '3.2.2'
  , item = eval('z[' + path.replace(/[^\d\.]/g, '').split('.').join('][') + ']');

The line above:

• sanitizes the string by removing non numbers/decimals
• constructs a string “z[3][2][2]”
• evaluates this new string to give you the result directly.

You should wrap this in a try/catch in case anyone passes an invalid path.