# vue-debounce

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A simple to use directive for debounce solutions

It attaches itself to an event for actions

[![JavaScript Style Guide](https://cdn.rawgit.com/standard/standard/master/badge.svg)](https://github.com/standard/standard)

## Content

- [Features](#features)
- [Installation](#installation)
- [Modifiers](#modifiers)
- [Options](#options)
- [Option Defaults](#option-defaults)
- [Vue3 Setup](#vue3-setup)
- [Vue2 Setup](#vue2-setup)
- [Usage](#usage)
- [Modifier Usage](#modifier-usage)
- [Overwriting Events](#overwriting-events)
- [Use Just Debounce](#using-just-debounce)
- [Typescript Support](#typescript-support)
- [Caveats](#caveats)

## Features

- Dynamic debouncing for input based requests
- Easy to use, just place it into your vue instance and attach it to your inputs/components
- Self regulating no need to worry about it, set it and forget it
- Multiple time formats supported (miliseconds and seconds)
- Enter key support to automatically fire the desired function when the user hits the enter key in the desired input (Can also be disabled)
- Supports the ability to have multiple event listeners, and specify events at the element level

## Installation
```
npm i vue-debounce
```

## Modifiers

- `lock` : Used to lock the debounce and prevent the enter key from triggering the function when pressed
  - Example: `v-debounce:400ms.lock="cb"`
- `unlock` : Used to unlock the enter key on a debounced input, useful if you want to use the `lock` option and only want a few debounced inputs unlocked
- `fireonempty` : Use to signify that when that specific input is emptied, you want the function to fire right away
- `cancelonempty` : Use this to specify that when the input is emptied you **DO NOT** want your debounced function to trigger at all
- `trim` : `Boolean` - Tells debounce to trim out white space using the `String.prototype.trim()` function

## Options

- `lock` : `Boolean` - This works the same way as the modifier does, however using the option will lock _ALL_ of the debounced inputs within that vue instance, where as using the modifer only locks the one it's attached to
- `listenTo` : `String|Array` - Allows you to set a custom event attached to an element like `input` for example
  - This is given to the `addEventListener` method attached to the element
- `defaultTime` : `String` - Set the default timer for debounce directives that you don't give a time to
- `fireOnEmpty` : `Boolean` - Tells debounce that if the input is empty, then fire the function immediately
- `trim` : `Boolean` - Tells debounce to trim out white space using the `String.prototype.trim()` function

## Option Defaults

```js
{
  lock: false,
  listenTo: 'keyup',
  defaultTime: '300ms',
  fireOnEmpty: false,
  trim: false
}
```

## CDN Support

As of `v3.0.2` CDN support is fixed to work with ESM projects. If you need to use the esm setup simply import them like so:

```js
import debounce from 'https://unpkg.com/vue-debounce@3.0.2/dist/debounce.min.mjs';

// Or all of vue-debounce

import vueDebounce from 'https://unpkg.com/vue-debounce@3.0.2/dist/vue-debounce.min.mjs';
```

## Vue3 Setup

Usage has two flows based on which version of Vue you're currently using, if you use vue2 then those instructions are right below

With vue3 we simply need to import the new directive function `vue3Debounce` this function takes in an object of options (found above)

Using `vue-debounce` Globally:
```js
import { vue3Debounce } from 'vue-debounce'
import { createApp } from 'vue';
import App from './App.vue';

const app = createApp(App)
app
  .directive('debounce', vue3Debounce({ lock: true }))
  .mount('#app');
```

Using `vue-debounce` at a component level:
```js
import { vue3Debounce } from 'vue-debounce'

export default {
  directives: {
    debounce: vue3Debounce({ lock: true })
  }
}
```

## Vue2 Setup

First make sure we tell vue to use it

```js
import Vue from 'vue'
import vueDebounce from 'vue-debounce'

Vue.use(vueDebounce)

// Or if you want to pass in the lock option
Vue.use(vueDebounce, {
  lock: true
})

// Setting a different event to listen to
Vue.use(vueDebounce, {
  listenTo: 'input'
})

// Listening to multiple events
Vue.use(vueDebounce, {
  listenTo: ['input', 'keyup']
})

// Setting a default timer This is set to '300ms' if not specified
Vue.use(vueDebounce, {
  defaultTime: '700ms'
})
```

## Usage

Then attach a time:format to the directive, and set the value to the function you want to call and attach it to your input element

Example:

```vue
<input v-debounce:300ms="myFunc" type="text" />
```

If no wait timer is passed in, then the directive will default to whatever you set `defaultTime` to, **OR** `300ms` if that isn't set.

You can pass the time in multiple formats:

```vue
<!-- If no time format is attached ms is used -->
<input v-debounce:300="myFunc" type="text" />

<!-- Seconds format is supported -->
<input v-debounce:1s="myFunc" type="text" />
```

The value of the input is passed along to your function as the first parameter, and the 2nd parameter is the event object itself.

## Modifier Usage

Using modifiers works just like normal Vue directives. You can chain them to the timeout value and each other. Some examples include:

> **IMPORTANT NOTE**: Modifiers WILL overwrite options you have set, for example if you set the `fireOnEmpty` option set to true and then tag a input with the `cancelonempty` modifier then the debounced function will cancel when **THAT** input is empty instead of fire.

```vue
<!-- Using Modifiers locking the input so the enter key isn't registered -->
<input v-debounce:1s.lock="myFunc" type="text" />

<!-- Using Modifiers unlocking the input so the enter key is registered -->
<!-- If you've set lock to true as an option when adding this module -->
<input v-debounce:1s.unlock="myFunc" type="text" />

<!-- Using the fireonempty modifier triggers your debounced function when this specific input field is empty -->
<input v-debounce:1s.fireonempty="myFunc" type="text" />

<!-- Using the cancelonempty modifier tells debounce to cancel function execution when the field is empty -->
<input v-debounce:1s.cancelonempty="myFunc" type="text" />
```

## Overwriting Events

As of Version 1.2.0 you can assign specific event listeners to specific inputs. Doing so overwrites **ANY** of the listed events set with `listenTo`

Example:
```vue
// This can accept an array or a single string when using the bind `:` syntax
<input v-debounce:1s="myFunc" :debounce-events="['click', 'keydown']">
<input v-debounce:1s="myFunc" :debounce-events="'click'">

// You can also just use it as an attribute, though if passing multiple events binding it is preferred
<input v-debounce:1s="myfunc" debounce-events="click">
```

A full example:

```vue
<template>
  <input v-debounce:400ms="myFn" type="text" />
  <input v-debounce:400ms="myFn" debounce-events="click" type="text" />
</template>
<script>
export default {
  methods: {
    myFn(val, e) {
      console.log(val) // => The value of the input
      console.log(e) // => The event object
    }
  }
}
</script>
```

## Using Just Debounce

With Vue-debounce you're also able to just use the debouncing function.

Simply require the debounce file.

```js
import { debounce } from 'vue-debounce'
```

The `debounce` function returns a function back which in turn is debounced, so you can set them up ahead of time:

```js
const dFn = debounce(val => console.log('normal format', val), '400ms')

dFn(10) // => 'normal format' 10
// Or
debounce(val => console.log('just a number!'), 400)(10) // => 'just a number!' 10
```

## Typescript Support
While this project is not written in typescript, we do define types in the `types` directory. Unfortunately the way Vue is currently typed
the only type support you will get is when you `Vue.use(vueDebounce)`.

i.e.

```typescript
import Vue from 'vue'
import vueDebounce, { PluginConfig, debounce } from 'vue-debounce'

debounce(() => console.log('just a number!'), 400)
debounce(() => console.log('normal format'), '400ms')

Vue.use<PluginConfig>(vueDebounce, { lock: true, defaultTime: '400ms', listenTo: 'keyup' })
```

Hopefully in the future Vue will allow directives to type the modifiers and values that are accepted.

## Caveats

If a library you are using such as `Vueftify` is already using a specified event, it will block vue debounce from being able to listen to that event.

As of `v3.1.0` I have significantly improved compatability with these kinds of libraries, however this problem still remains.

For example, Vuetify makes pretty heavy use of the `onblur` event for a lot of it's styles/animatons, so I'd recommend telling vue-debounce to listen for `focusout` instead, if you want debounce to trigger on a blur like event.

I will keep doing research into a better way to solve this little issue, but for now the improved compatability should help a lot!