Truncate a number to particular decimal places without rounding

function toFixed(num, fixed) {
    var re = new RegExp('^-?\\d+(?:\.\\d{0,' + (fixed || -1) + '})?');
    return num.toString().match(re)[0];
}

Example

toFixed(1.05, 1) //1.0
toFixed(1.05, 0) //1