Is it possible to get the index you're sorting over in Underscore.js?

Index is actually available like;

_.sortBy([1, 4, 2, 66, 444, 9], function(num, index){  });

You can get the index of the current iteration by adding another parameter to your iterator function, e.g.

_.each(['foo', 'bar', 'baz'], function (val, i) {
    console.log(i + ": " + val); // 0: foo, 1: bar, 2: baz
});

If you'd rather transform your array, then the iterator parameter of underscore's map function is also passed the index as a second argument. So:

_.map([1, 4, 2, 66, 444, 9], function(value, index){ return index + ':' + value; });

... returns:

["0:1", "1:4", "2:2", "3:66", "4:444", "5:9"]

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