Make any base-10 integer binary

make-binary.js

function makeBinary() {
    var str = '';
    // get input from form field
    var input = +document.getElementById('number').value;
    // try subtracting every place in a 32-bit integer
    for (var i = 32; i > -1; i--) {
        var raised = Math.pow(2,i);
        if (input - raised > -1) {
            str += '1';
            input -= raised;
        } else {
            str += '0';
        }
    }
    // erase trailing zeroes
    while (str.substr(0, 1) == '0') {
        str = str.substr(1);
    }
    document.write(str);
}