SOURCE

function fun1(a, b,c) {
    console.log("*this: ", this)
    console.log(a, b,c)
    return 'this is fun1'
}

Function.prototype.bind1 = (thisArg, ...argsArry) =>{
    const self = this
    return function () {
        return self.apply(thisArg, argsArry)
    }
}

const fun2 = fun1.bind1({x: 100}, 2, 6, 4)
const ret = fun2()
console.log(ret)