function hook(object, attr) {
    var func = object[attr]
    object[attr] = function () {
        console.log('hooked', object, attr)
        var ret = func.apply(object, arguments)
        debugger
        return ret
    }
}
hook(window, 'btoa')
const form = {
    username: "admin",
    password: "admin"
}

const a = window['btoa'].apply(JSON.stringify(form))
console.log(a)