浮点数递增

/**
 * [float_add 浮点数加加]
 * @param  {[type]} _num [description]
 * @return {[type]}      [description]
 */
function float_add(_num){
    var r1, r2, m, arg;
    try {
        r1 = _num.toString().split(".")[1].length;
    } catch (e) {
        r1 = 0
    }
    arg = 1/Math.pow(10,r1);
    try {
        r2 = arg.toString().split(".")[1].length;
    } catch (e) { 
        r2 = 0 
    }
    m = Math.pow(10, Math.max(r1, r2));
    return (_num * m + arg * m) / m;
}

效果如图