Javascript binding function to an object

Question

const person = {
    name: "Mike",
    country: "New Zealand"
}

function personUpdate(name, country) {
    this.name = name
    this.country = country
}

personUpdate.bind(person)

personUpdate('Tony', 'Chile')

Why doesn't this work? person still has original properties 'Mike' and 'New Zealand'. Why doesn't personUpdate.bind(person) I want to make it so that every call to personUpdate the this refers to the person object (and without using new).

var boundPersonUpdate = personUpdate.bind(person); boundPersonUpdate('Tony', 'Chile'); — kangsu
– kangsu, Commented Jul 4, 2017 at 1:48

user94559 · Accepted Answer · 2017-07-04 01:50:50Z

2

Calling .bind doesn't modify the function you pass in; it returns a new bound function.

So you want either:

var boundPersonUpdate = personUpdate.bind(person);
boundPersonUpdate(...); // call the bound version

or:

personUpdate = personUpdate.bind(person); // overwrite the original function

answered Jul 4, 2017 at 1:50

user94559

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Comments

Rence · Accepted Answer · 2017-07-04 02:05:12Z

0

I have tried your code and I think nothing is wrong with it.

const person = {
name: "Mike",
country: "New Zealand"
}
function personUpdate(name, country) {
this.name = name;
this.country = country;

console.log(this.name);
console.log(this.country);
}
personUpdate.bind(person);
personUpdate('Tony', 'Chile');

I tried to print it and it is giving me "Tony" and "Chile", or I misunderstood your question?

answered Jul 4, 2017 at 2:05

Rence

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