var str = '13131.9090013';
// 字符串转数值类型
console.log(parseInt(str)); //13131
console.log(parseFloat(str)); //13131.9090013
console.log(typeof parseFloat(str)); //number
var a = Number(str);
console.log(isNaN(a)); //NaN //false
var num = 1313.179;
// 强制类型转换
console.log(num.toString()); //1313.179
console.log(typeof num.toString()); //string
console.log(String(num)); //1313.179
// 隐式转换
console.log('' + num); //1313.179
console.log(''.concat(num)); //1313.179
console.log(Number(num.toFixed(2))); //1313.18