📚 23.trim

💻 代码实现

String.prototype._trim = function () {
    let left = 0,
        right = this.length - 1
    for (let i = 0; i < this.length; i++) {
        if (this[i] === " ") {
            left++
        } else {
            break
        }
    }
    for (let i = right; i >= 0; i--) {
        if (this[i] === " ") {
            right--
        } else {
            break
        }
    }
    return this.slice(left, right + 1)
}

let str = "    hello     ww   "
console.log(str._trim())