I have a simple input box in a Vue template and I would like to use debounce more or less like this:
<input type="text" v-model="filterKey" debounce="500">
However the debounce
property has been deprecated in Vue 2. The recommendation only says: "use v-on:input + 3rd party debounce function".
How do you correctly implement it?
I've tried to implement it using lodash, v-on:input and v-model, but I am wondering if it is possible to do without the extra variable.
In template:
<input type="text" v-on:input="debounceInput" v-model="searchInput">
In script:
data: function () {
return {
searchInput: '',
filterKey: ''
}
},
methods: {
debounceInput: _.debounce(function () {
this.filterKey = this.searchInput;
}, 500)
}
The filterkey is then used later in computed
props.
I am using debounce NPM package and implemented like this:
<input @input="debounceInput">
methods: {
debounceInput: debounce(function (e) {
this.$store.dispatch('updateInput', e.target.value)
}, config.debouncers.default)
}
Using lodash and the example in the question, the implementation looks like this:
<input v-on:input="debounceInput">
methods: {
debounceInput: _.debounce(function (e) {
this.filterKey = e.target.value;
}, 500)
}
Option 1: Re-usable, no deps
- Recommended if needed more than once in your project
/helpers.js
export function debounce (fn, delay) {
var timeoutID = null
return function () {
clearTimeout(timeoutID)
var args = arguments
var that = this
timeoutID = setTimeout(function () {
fn.apply(that, args)
}, delay)
}
}
/Component.vue
<script>
import {debounce} from './helpers'
export default {
data () {
return {
input: '',
debouncedInput: ''
}
},
watch: {
input: debounce(function (newVal) {
this.debouncedInput = newVal
}, 500)
}
}
</script>
Option 2: In-component, also no deps
- Recommended if using once or in small project
/Component.vue
<template>
<input type="text" v-model="input" />
</template>
<script>
export default {
data: {
timeout: null,
debouncedInput: ''
},
computed: {
input: {
get() {
return this.debouncedInput
},
set(val) {
if (this.timeout) clearTimeout(this.timeout)
this.timeout = setTimeout(() => {
this.debouncedInput = val
}, 300)
}
}
}
}
</script>
[Vue warn]: Error in callback for watcher "input": "TypeError: Cannot read property 'call' of undefined"
Assigning debounce in methods
can be trouble. So instead of this:
// Bad
methods: {
foo: _.debounce(function(){}, 1000)
}
You may try:
// Good
created () {
this.foo = _.debounce(function(){}, 1000);
}
It becomes an issue if you have multiple instances of a component - similar to the way data
should be a function that returns an object. Each instance needs its own debounce function if they are supposed to act independently.
Here's an example of the problem:
Vue.component('counter', { template: '
data()
then.
Very simple without lodash
handleScroll: function() {
if (this.timeout)
clearTimeout(this.timeout);
this.timeout = setTimeout(() => {
// your action
}, 200); // delay
}
destroyed() { clearInterval(this.timeout) }
in order to not having a timeout after destroyed.
I had the same problem and here is a solution that works without plugins.
Since <input v-model="xxxx">
is exactly the same as
<input
v-bind:value="xxxx"
v-on:input="xxxx = $event.target.value"
>
I figured I could set a debounce function on the assigning of xxxx in xxxx = $event.target.value
like this
<input
v-bind:value="xxxx"
v-on:input="debounceSearch($event.target.value)"
>
methods:
debounceSearch(val){
if(search_timeout) clearTimeout(search_timeout);
var that=this;
search_timeout = setTimeout(function() {
that.xxxx = val;
}, 400);
},
@input="update_something"
action then call this after that.xxx = val
that.update_something();
debounceSearch: function(val) { if (this.search_timeout) clearTimeout(this.search_timeout); var that=this; this.search_timeout = setTimeout(function() { that.thread_count = val; that.update_something(); }, 500); },
If you need a very minimalistic approach to this, I made one (originally forked from vuejs-tips to also support IE) which is available here: https://www.npmjs.com/package/v-debounce
Usage:
<input v-model.lazy="term" v-debounce="delay" placeholder="Search for something" />
Then in your component:
<script>
export default {
name: 'example',
data () {
return {
delay: 1000,
term: '',
}
},
watch: {
term () {
// Do something with search term after it debounced
console.log(`Search term changed to ${this.term}`)
}
},
directives: {
debounce
}
}
</script>
Please note that I posted this answer before the accepted answer. It's not correct. It's just a step forward from the solution in the question. I have edited the accepted question to show both the author's implementation and the final implementation I had used.
Based on comments and the linked migration document, I've made a few changes to the code:
In template:
<input type="text" v-on:input="debounceInput" v-model="searchInput">
In script:
watch: {
searchInput: function () {
this.debounceInput();
}
},
And the method that sets the filter key stays the same:
methods: {
debounceInput: _.debounce(function () {
this.filterKey = this.searchInput;
}, 500)
}
This looks like there is one less call (just the v-model
, and not the v-on:input
).
debounceInput()
twice for each change? v-on:
will detect the input changes and call debounce, AND because the model is bound, searchInput's watch function will ALSO call debounceInput
... right?
In case you need to apply a dynamic delay with the lodash's debounce
function:
props: {
delay: String
},
data: () => ({
search: null
}),
created () {
this.valueChanged = debounce(function (event) {
// Here you have access to `this`
this.makeAPIrequest(event.target.value)
}.bind(this), this.delay)
},
methods: {
makeAPIrequest (newVal) {
// ...
}
}
And the template:
<template>
//...
<input type="text" v-model="search" @input="valueChanged" />
//...
</template>
NOTE: in the example above I made an example of search input which can call the API with a custom delay which is provided in props
Although pretty much all answers here are already correct, if anyone is in search of a quick solution I have a directive for this. https://www.npmjs.com/package/vue-lazy-input
It applies to @input and v-model, supports custom components and DOM elements, debounce and throttle.
Vue.use(VueLazyInput) new Vue({ el: '#app', data() { return { val: 42 } }, methods:{ onLazyInput(e){ console.log(e.target.value) } } })
To create debounced methods you can use computeds, that way they won't be shared across multiple instances of your component:
<template>
<input @input="handleInputDebounced">
<template>
<script>
import debounce from 'lodash.debouce';
export default {
props: {
timeout: {
type: Number,
default: 200,
},
},
methods: {
handleInput(event) {
// input handling logic
},
},
computed: {
handleInputDebounced() {
return debounce(this.handleInput, this.timeout);
},
},
}
</script>
You can make it work with uncontrolled v-model
as well:
<template>
<input v-model="debouncedModel">
<template>
<script>
import debounce from 'lodash.debouce';
export default {
props: {
value: String,
timeout: {
type: Number,
default: 200,
},
},
methods: {
updateValue(value) {
this.$emit('input', value);
},
},
computed: {
updateValueDebounced() {
return debounce(this.updateValue, this.timeout);
},
debouncedModel: {
get() { return this.value; },
set(value) { this.updateValueDebounced(value); }
},
},
}
</script>
If you are using Vue you can also use v.model.lazy
instead of debounce
but remember v.model.lazy
will not always work as Vue limits it for custom components.
For custom components you should use :value
along with @change.native
<b-input :value="data" @change.native="data = $event.target.value" ></b-input>
1 Short version using arrow function, with default delay value
file: debounce.js in ex: ( import debounce from '../../utils/debounce' )
export default function (callback, delay=300) {
let timeout = null
return (...args) => {
clearTimeout(timeout)
const context = this
timeout = setTimeout(() => callback.apply(context, args), delay)
}
}
2 Mixin option
file: debounceMixin.js
export default {
methods: {
debounce(func, delay=300) {
let debounceTimer;
return function() {
// console.log("debouncing call..");
const context = this;
const args = arguments;
clearTimeout(debounceTimer);
debounceTimer = setTimeout(() => func.apply(context, args), delay);
// console.log("..done");
};
}
}
};
Use in vueComponent:
<script>
import debounceMixin from "../mixins/debounceMixin";
export default {
mixins: [debounceMixin],
data() {
return {
isUserIdValid: false,
};
},
mounted() {
this.isUserIdValid = this.debounce(this.checkUserIdValid, 1000);
},
methods: {
isUserIdValid(id){
// logic
}
}
</script>
another option, example
I was able to use debounce with very little implementation.
I am using Vue 2.6.14 with boostrap-vue:
Add this pkg to your package.json: https://www.npmjs.com/package/debounce
Add this to main.js:
import { debounce } from "debounce";
Vue.use(debounce);
In my component I have this input:
<b-form-input
debounce="600"
@update="search()"
trim
id="username"
v-model="form.userName"
type="text"
placeholder="Enter username"
required
>
</b-form-input>
All it does is call the search() method and the search method uses the form.userName for perform the search.
If you could move the execution of the debounce function into some class method you could use a decorator from the utils-decorators lib (npm install --save utils-decorators
):
import {debounce} from 'utils-decorators';
class SomeService {
@debounce(500)
getData(params) {
}
}
public debChannel = debounce((key) => this.remoteMethodChannelName(key), 200)
vue-property-decorator
Success story sharing
v-model=your_input_variable
to the input and in your vuedata
. So you do not rely one.target
but use Vue so you can accessthis.your_input_variable
instead ofe.target.value
this
within the function.