sum, range, and fibonacci

gistfile1.js

function range(start, end) {
    var output = [];
    for(var i = start; i <= end; i++) {
        output.push(i);
    }
    return output;
}
// console.log(range(1,10));

function sum(array) {
    var output = 0;
    for(var i = 0; i < array.length; i++) {
        output += array[i];
    }
    return output;
}
// console.log(sum([1,2,3,4,5]));

function fibonacci(length) {
    var output = [0,1];
    for (var i = 2; i < length; i++) {
        var last = output[output.length-1];
        var nextToLast = output[output.length-2];
        output.push(last + nextToLast);
    }
    return output;
}
// console.log(fibonacci(2)); // [0,1]
// console.log(fibonacci(5)); // [0,1,1,2,3]