将字符串转换为1行的2十进制数字

Question

我有一个字符串123.4567，我想转换为两个小数的数字，我想在Javascript中的1短行中做到这一点。

const x = "123.4567";
// this works but seems way too cumbersome
const y = parseFloat((parseFloat(x)).toFixed(2))
console.log(typeof(y) + " / " + y)      //Prints: number / 123.45
// this I expected to work but it doesn't
const z = (parseFloat(x)).toFixed(2)
console.log(typeof(z) + " / " + z)      //Prints: string / 123.45

Answer 1

你可以这样做:

const
x = "123.4567" 
, y = (0 | (parseFloat(x) *100)) /100 // or (0|parseFloat(x) *100) /100 - see JS Operator precedence
, z = +(+x).toFixed(2)                // use + for type cast number
, w = +(0 || x.match(/d*.?d{0,2}/)[0])  // best regex i can do...
;

console.log(`${typeof y} / ${y}`)  // number / 123.45
console.log(`${typeof z} / ${z}`)  // number / 123.46  the same + 0.01 (rounding)
console.log(`${typeof w} / ${w}`)  // number / 123.45

Nb:( 0 | number )返回任意浮点数的整数部分(|=二进制或运算符)