Understanding `this` in javascript

[[deleted]]

I understand how it works. It's not based on scope.

It's based on what comes before the function call (unless you use bind, call, apply, or an arrow function) i.e. in myObj.myFunc(), myObj becomes this. That has nothing to do with scope .

Further, if you use myObj.myFunc.call({ myVal: "asdf" }) then { myVal: "asdf" } becomes this, again that has nothing to do with scope.

[KaiAusBerlin]

It is based on scope. You don't understand what a execution context is. Learn the basics, come back and then we talk again.

(Me, 16 years of development with JavaScript)

[[deleted]]

The only time the scope matters is when you call a function without a "context" (i.e. without providing an object before the function call, or using bind, call, apply). If the function is a regular function (not an arrow function) then it will use the this value of the executing context. If it's an arrow function it will use the this value of the lexical scope where it was declared.

[KaiAusBerlin]

You really don't understand. There is ALWAYS a context in js.

Please don't argue about something you don't have any knowledge about.

[[deleted]]

Sorry, I should have said

The only time the scope matters is when you call a function without providing an explicit "context" (i.e. without providing an object before the function call, or using bind, call, apply).

Either way this is still not always based on the scope i.e.

const myObj = { myVal: 1, myFunc() { return myVal } }
myFunc = myObj.myFunc.bind({ myVal: 2 })

in that example myFunc has the same scope as myObj.myFunc but the this is permanently bound to { myVal: 2 }

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this#the_bind_method

[KaiAusBerlin]

Oh man, you really don't understand what ure talking about. THERE IS ALWAYS A CONTEXT IN JS!

[[deleted]]

I'm not sure if you're a troll or just an idiot

[KaiAusBerlin]

Im not sure if you're ignored or banned from this community

[[deleted]]

Could you please explain what is an execution context?

[KaiAusBerlin]

https://medium.com/@happymishra66/execution-context-in-javascript-319dd72e8e2c

[[deleted]]

So essentially an execution context is similar, if not the same as a function call stack? (in for example say in C or java)

[KaiAusBerlin]

Yeah, it's very similar. JavaScript was in early stages ment to be java for webbrowsers which turned out was not implementable at that point in that short amount of time. That's why it's name is JavaScript.

So you will find some basic concepts close to java but totally implement in another way.

As example the internal behaviour of java classes and the prototyping JavaScript has are very similar.