Self-references in object literals / initializers
When working with JavaScript, you may come across a situation where you need to reference a property within the same object literal or initializer. This can be a bit tricky, but there are a few ways to achieve it.
1. Using a temporary variable
One way to reference a property within the same object literal is by using a temporary variable. Here’s an example:
const myObject = {
property1: 'Hello',
property2: 'World',
property3: null,
};
myObject.property3 = myObject.property1 + ' ' + myObject.property2;
console.log(myObject.property3); // Output: Hello World
In this example, we create an object called myObject
with three properties: property1
, property2
, and property3
. We then assign the value of property1
concatenated with a space and property2
to property3
. Finally, we log the value of property3
to the console, which will output Hello World
.
2. Using a getter method
Another way to reference a property within the same object literal is by using a getter method. Here’s an example:
const myObject = {
property1: 'Hello',
property2: 'World',
get property3() {
return this.property1 + ' ' + this.property2;
},
};
console.log(myObject.property3); // Output: Hello World
In this example, we define a getter method called property3
within the object literal. The getter method returns the value of property1
concatenated with a space and property2
. When we access myObject.property3
, it will execute the getter method and return Hello World
.
3. Using Object.assign()
If you want to create a new object with self-references, you can use the Object.assign()
method. Here’s an example:
const myObject = {
property1: 'Hello',
property2: 'World',
};
const newObj = Object.assign({}, myObject, {
property3: myObject.property1 + ' ' + myObject.property2,
});
console.log(newObj.property3); // Output: Hello World
In this example, we use Object.assign()
to create a new object called newObj
. We pass an empty object as the first parameter, followed by myObject
and an object literal with property3
set to the value of myObject.property1
concatenated with a space and myObject.property2
. When we access newObj.property3
, it will return Hello World
.
These are three different ways to reference properties within the same object literal or initializer in JavaScript. Choose the one that best suits your needs and coding style.
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