What information is stored within a JavaScript variable?

Question

What information is stored within a JavaScript variable?

After researching JSON, I began to question what would happen if a JSON path (for instance: foo.bar) is stored in a variable and then called. Would it call foo.bar itself, or whatever value is contained within foo.bar?

Update: I'll provide an example:

var json = { "foo": { "bar": "some value" } };
var container = json.foo.bar;
document.write(contaier);
//Is this equivalent to document.write(json.foo.bar);
//Or is it equivalent to document.write("some value");
//I understand that in this specific scenario, it may not serve any practical purpose, but it could be useful for manipulating the path.

javascript json variables

Answer 1

Answer №1

Functions cannot be serialized in JSON, meaning that foo.bar will never be treated as a function. Attempting to call it will result in an Error being thrown.

In terms of pass-by-value vs pass-by-reference: If foo.bar is an Object, you will receive a reference. However, if it is a scalar value (such as a number or string), you will get the actual value.

Answer 2

Functions cannot be serialized in JSON, meaning that foo.bar will never be treated as a function. Attempting to call it will result in an Error being thrown.

In terms of pass-by-value vs pass-by-reference: If foo.bar is an Object, you will receive a reference. However, if it is a scalar value (such as a number or string), you will get the actual value.

Answer 3

Answer №2

Performing document.write("some value"); has an equivalent effect.

In this scenario, the variable holds a duplicated version of the property's value, which is a string. Essentially, the variable contains a duplicate reference to the string.

If modifications are made to the object's content (which isn't JSON but rather a JavaScript object) after extracting the value into the variable, the variable retains its original value:

var obj = { "foo": { "bar": "some value" } };
var container = obj.foo.bar;
obj.foo.bar = "some other value";
document.write(container); // displays "some value"

Answer 4

Performing document.write("some value"); has an equivalent effect.

In this scenario, the variable holds a duplicated version of the property's value, which is a string. Essentially, the variable contains a duplicate reference to the string.

If modifications are made to the object's content (which isn't JSON but rather a JavaScript object) after extracting the value into the variable, the variable retains its original value:

var obj = { "foo": { "bar": "some value" } };
var container = obj.foo.bar;
obj.foo.bar = "some other value";
document.write(container); // displays "some value"

Answer 5

Answer №3

To illustrate this concept, let me demonstrate with some simple lines of code:

var data = {
    foo: {
        bar: 'case 1'
    },
    'foo.bar': 'case 2'
};

console.log(data.foo.bar); // 'case 1'
console.log(data['foo.bar']); // 'case 2'
console.log(data['foo']['bar']); // 'case 1'

Situation 1

In the first scenario, there is a property foo that contains an object with the property bar holding the string case 1.

Situation 2

In the second instance, there exists a property named foo.bar which holds the string case 2

Answer 6

To illustrate this concept, let me demonstrate with some simple lines of code:

var data = {
    foo: {
        bar: 'case 1'
    },
    'foo.bar': 'case 2'
};

console.log(data.foo.bar); // 'case 1'
console.log(data['foo.bar']); // 'case 2'
console.log(data['foo']['bar']); // 'case 1'

Situation 1

In the first scenario, there is a property foo that contains an object with the property bar holding the string case 1.

Situation 2

In the second instance, there exists a property named foo.bar which holds the string case 2

Answer 7

Answer №4

let obj = { "name": { "age": 25 } };

You are assigning the object literal { "name": { "age": 25 } } to the variable obj.

let ageValue = obj.name.age;

In this line of code, you are assigning the value of the age property inside the name property of obj to the variable ageValue. This assignment works by assigning the actual value on the right side of the expression to the left side variable, which in this case is 25.

Answer 8

let obj = { "name": { "age": 25 } };

You are assigning the object literal { "name": { "age": 25 } } to the variable obj.

let ageValue = obj.name.age;

In this line of code, you are assigning the value of the age property inside the name property of obj to the variable ageValue. This assignment works by assigning the actual value on the right side of the expression to the left side variable, which in this case is 25.

What information is stored within a JavaScript variable?

Answer №1

Answer №2

Answer №3

Situation 1

Situation 2

Answer №4

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