How do you write functions in ES6?

Question

How do you write functions in ES6?

When attempting to access my namespaced store in Vue, I encountered an issue:

methods: {
    ...mapActions('Modal', [
        'toggleActive',
    ]),
    close: () => {
        this.toggleActive();
    }

This resulted in the following error message:

Uncaught TypeError: Cannot read property 'toggleActive' of undefined

However, when I made a slight adjustment like so:

close: function() {
    this.toggleActive();
}

I was able to resolve the issue. How can I effectively implement ES6 function syntax with vue/vuex?

javascript vue.js vuejs2 vuex

Answer 1

Answer №1

When using arrow functions, they will close over the this in the context of where they're defined, instead of having it set when called like regular function functions do. For example:

// `this` refers to the current context here
var o = {
    foo: () => {
        // ...will also refer to the same context as above when `foo` is called
    }
};

To avoid this behavior, it's recommended to use method syntax instead:

methods: {
    // Using a simple method for toggleActive for clarity; if you're transpiling with a tool that understands rest notation for objects, your `mapActions` should be fine *assuming* the functions it creates are not arrow functions
    toggleActive() {
        // ...
    },
    close() {
        this.toggleActive();
    }
};

Keep in mind that this approach is subject to the usual challenges related to the this keyword, which you can read about in detail in the answers provided in this question on Stack Overflow: described in this question's answers.

Answer 2

When using arrow functions, they will close over the this in the context of where they're defined, instead of having it set when called like regular function functions do. For example:

// `this` refers to the current context here
var o = {
    foo: () => {
        // ...will also refer to the same context as above when `foo` is called
    }
};

To avoid this behavior, it's recommended to use method syntax instead:

methods: {
    // Using a simple method for toggleActive for clarity; if you're transpiling with a tool that understands rest notation for objects, your `mapActions` should be fine *assuming* the functions it creates are not arrow functions
    toggleActive() {
        // ...
    },
    close() {
        this.toggleActive();
    }
};

Keep in mind that this approach is subject to the usual challenges related to the this keyword, which you can read about in detail in the answers provided in this question on Stack Overflow: described in this question's answers.

How do you write functions in ES6?

Answer №1

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