Object literal constructor

I am looking for a way to modify an object that was defined by a literal without passing it into another function.

example:

let o = a:1,b:2
console.log(o.a===3)


i thought when i define an object using a literal the the Object constructor would be called, so i did override Object.prototype.constructor but it only gets called when i do new Object(a:1,b:2)

Object.prototype.constructor

new Object(a:1,b:2)

question in simpler terms can anyone make a=3 without passing the object o to a function or a proxy or using o.a=3 or with keyword, where o is defined using an object literal?

a=3

o.a=3

with

o

4 Answers
4

It's simply not possible.

There is no constructor of an object literal.

You can create objects in different ways:

Object.create

Also, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer

Just do o.a=3; and console log o:

o.a=3;

o

let o = a:1,b:2;
o.a=3;
console.log(o);

Currently you are doing o.a===3 which will return Boolean value instead of overwriting the value of property a.

o.a===3

Boolean

a

You also cannot do o.a=3 inside console.log() because o.a=3 will return the assigned value which is 3 but it will still change the property a of o to 3.

o.a=3

console.log()

o.a=3

3

a

o

3

let o =
a: 1,
b: 2
;
//won't print o but changes o.a to 3
console.log(o.a = 3);

question in simpler terms can anyone make a=3 without passing the object o to a function or a proxy?

o.a = 3;


I am looking for a way to modify an object that was defined by a literal without passing it into another function.

Thats impossible, cause if it would be possible you could break every piece of javascript. And that would be terrible.

Oh wait, this is JS...

with( get o() return a: 3 ; , set o(v) )

o = a:1,b:2;
console.log(o.a===3) // true




What you want to achieve could be done if o.a holds a reference to the variable a - which unfortunately only works the way you'd like for variables that are passed by reference. Primitive types like String, Number and Boolean though, are passed by value.

o.a

a

String

Number

Boolean

Check the examples below:

var a = 1;

var o = a: a ;

a = 2;

console.log(o.a, a);

It also doesn't help to use an Object constructor like new Number() because that does return a reference to an object (which is passed by reference as you'd need), but assigning a new value to it reading the value still returns a primitive (which is, again, passed by value):

new Number()

var a = new Number(1);

var o = a: a.valueOf() ;

a = Number(2);

console.log(o.a, a);

If you pass something that is naturally passed by reference, your expectation is fulfilled:

var a = [ 1 ]

var o = a: a

a[0] = 2

console.log(o.a[0])

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