Debouncing/throttling a method using Vue Class Component Syntax

user_3536464 0
Viewed 2565

I'm working on a component which queries an external API when the text in a search bar changes, and I'm trying to debounce that query so it can only execute every 2 seconds. I'm trying to use lodash's debounce function to do that, and have found multiple blog posts and SO questions about using it with Vue components, but things are complicated because I am using Typescript and the Vue Class Component Syntax (https://class-component.vuejs.org/). And to be honest I'm quite new to both of those.

I found a blog post outlining how to do this with object-based Vue component syntax, but it doesn't apply to the Class Component Syntax. The object-based syntax allows you to wrap your methods inside a _.debounce, like this:

export default {
  methods: {
    throttledMethod: _.debounce(() => {
      console.log('I only get fired once every two seconds, max!')
    }, 2000)
  }
}

Is there a way to do something similar with the Vue Class Component syntax?

Here are the relevant sections of my code (without any attempts at debouncing):

<template>
  <input
    v-model="searchQuery"
    @keydown="doSearch"
  >
</template>

<script lang="ts">
import axios from 'axios';
import _ from 'lodash';
import { Component, Vue } from 'vue-property-decorator';

@Component
export default class FooSearch extends Vue {
  // data
  searchQuery = '';
  results = [];

  // methods
  async doSearch() {
    try {
      const response = await axios.get('https://api.example.org/search', {
        params: {
          query: this.searchQuery,
        }
      });

      this.results = response.data.results;
    } catch(error) {
      console.log('error');
      console.log(error);
    }
  }
</script>
lodash vue-class-components vue.js typescript
3 Answers

It has been discussed here.

Basically, you need to define your base function (like you did with doSearch) and then define the new debounced function:

public doSearchDebounced = _.debounce(this.doSearch, 2000)

Now yu simply need to call doSearchDebounced instead of doSearch

user_48618730

Although the above has been answered, I think we should make good use of createDecorator in vue-class-component and integrate lodash to simplify the use of Debounce and Throttle.

Create decorator.ts


import { createDecorator } from "vue-class-component";
import _ from "lodash";

export const Debounce = (waitMs: number) =>
  createDecorator((options, key) => {
    if (options.methods && options.methods[key]) {
      const originalMethod = options.methods[key];
      const debounceMethod = _.debounce(originalMethod, waitMs, {
        leading: false,
        trailing: true,
      });

      options.methods[key] = async function (...args: any) {
        await debounceMethod.apply(this, args);
      };
    }
  });

export const Throttle = (waitMs: number) =>
  createDecorator((options, key) => {
    if (options.methods && options.methods[key]) {
      const originalMethod = options.methods[key];
      const throttleMethod = _.throttle(originalMethod, waitMs, {
        leading: true,
        trailing: false,
      });

      options.methods[key] = async function (...args: any) {
        await throttleMethod.apply(this, args);
      };
    }
  });

Refactor code and use decorator.

<template>
  <input
    v-model="searchQuery"
    @keydown="doSearch"
  >
</template>

<script lang="ts">
import axios from 'axios';
import { Component, Vue } from 'vue-property-decorator';
import { Debounce } from "@/decorator";

@Component
export default class FooSearch extends Vue {
  // data
  searchQuery = '';
  results = [];

  // add the Debounce annotation
  @Debounce(1500)
  async doSearch() {
    try {
      const response = await axios.get('https://api.example.org/search', {
        params: {
          query: this.searchQuery,
        }
      });

      this.results = response.data.results;
    } catch(error) {
      console.log('error');
      console.log(error);
    }
  }
</script>
user_50468870

you can do it like that

<script lang='ts'>   
 import { debounce } from 'decko'

@debounce(1000)
 async doSearch() {
....
}
</script>
user_67146570
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