两个大数相加

Question

实现两个大的整数相加，精度不会丢失

let a = "9007199254740991";
let b = "1234567899999999999";

function add(a, b) {
    const maxLen = Math.max(a.length, b.length)
    a = a.padStart(maxLen, 0)
    b = b.padStart(maxLen, 0)

    let f = 0
    let sum = ''
    for (let i = maxLen - 1; i >= 0; i--) {
        const t = parseInt(a[i]) + parseInt(b[i]) + f
        // 近位
        f = Math.floor(t / 10)
        sum = (t % 10) + sum
    }

    if (f > 0) {
        sum = f + sum
    }

    return sum
}

console.log(add(a, b))