Unusual Vue syntax: deconstructing `state` from `this.$store` with a default value of an

Question

Unusual Vue syntax: deconstructing `state` from `this.$store` with a default value of an

While working on a pre-existing project, I came across some interesting notation in a Vue project utilizing Vuex:

const { state = {} } = this.$store;
const { orders = {} } = state;

This code snippet appears to be creating a local object named "state" that is assigned the value from the Vuex store... and then further assigning that to another object called "orders." However, I find the notation itself a bit confusing. Specifically, I'm unsure about what this syntax signifies:

{ variable = {} } = anotherObj

I am curious to know if there is a specific name for this type of notation and whether it is commonly used outside of Vuex. My intention is to search for more information about how it handles deep cloning or if it has any particular implications related to object manipulation.

javascript vue.js vuex notation

Answer 1

Answer №1

Here's an explanation:

const { state = {} } = this.$store;

This is an example of utilizing destructuring assignment with a default value. In this case, if the property state in this.$store does not exist or has a value of undefined, it will default to an empty object. However, if the property exists and is not undefined, then state will be assigned the corresponding value from this.$store.state.

For better understanding, consider this example (although using strings instead of objects):

const obj1 = {};
const { a = "default" } = obj1;
console.log(a);        // "default"

const obj2 = {
    b: "value from obj2"
};
const { b = "default" } = obj2;
console.log(b);        // "value from obj2"

Answer 2

Here's an explanation:

const { state = {} } = this.$store;

This is an example of utilizing destructuring assignment with a default value. In this case, if the property state in this.$store does not exist or has a value of undefined, it will default to an empty object. However, if the property exists and is not undefined, then state will be assigned the corresponding value from this.$store.state.

For better understanding, consider this example (although using strings instead of objects):

const obj1 = {};
const { a = "default" } = obj1;
console.log(a);        // "default"

const obj2 = {
    b: "value from obj2"
};
const { b = "default" } = obj2;
console.log(b);        // "value from obj2"

Unusual Vue syntax: deconstructing `state` from `this.$store` with a default value of an

Answer №1

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