SOURCE

const wandou = {
    age: 27,
    printAge: function (value) {
        return this.age;
    }
}

const printAge = wandou.printAge;
console.log(printAge()) //undefined

const bindPrintAge = printAge.bind(wandou)
console.log(bindPrintAge()) //27


console.log("-----------------split line")

Function.prototype.bind1 = function () {
    const func = this
    const obj = Array.prototype.shift.call(arguments);
    const param = Array.prototype.slice.call(arguments);
    return function () {
        // apply 数组
        func.apply(obj, Array.prototype.concat.call(param,Array.prototype.slice.call(arguments)))
        // call 分别接受参数
    }
}
const bindPrintAge1 = wandou.printAge.bind1(wandou)
console.log(bindPrintAge1()) //27