How to access the index of an item in knockout.js template

Answer 1

Update: $index is now available in KO 2.1.

Currently, there is not a way to directly access the index in a foreach. There is a pull request that looks at adding a $index variable here: https://github.com/SteveSanderson/knockout/pull/182

An option that I have used in the past is to use a manual subscription against an observableArray that keeps an index observable in sync.

It works like:

//attach index to items whenever array changes
viewModel.tasks.subscribe(function() {
    var tasks = this.tasks();
    for (var i = 0, j = tasks.length; i < j; i++) {
       var task = tasks[i];
        if (!task.index) {
           task.index = ko.observable(i);  
        } else {
           task.index(i);   
        }
    }
}, viewModel);

Here is a sample: http://jsfiddle.net/rniemeyer/CXBFN/