The cast property on your component provides a convenient way of converting props to common data types.

Installation

yarn add vue-cast-props
# or
npm install vue-cast-props

Usage

import VueCastProps from 'vue-cast-props'

Vue.use(VueCastProps, /* options */)

export default {
  props: {
    active: {
      cast: 'string'
    }
  }
}

Now the active prop will always be cast to a string when you access it with $c.active.

<template>
  <div>Active {{ $c.active }}</div>
</template>

Supported types

The cast value should be an string or type.

export default {
  props: {
    age: {
      cast: Number
    }
  }
}

| As string | As type | Description | |-----------|---------|-------------| | array | Array | Cast to Array | | boolean | Boolean | Cast to Boolean | | function | Function | Cast to Function | | number | Number | Cast to Number | | date | Date | Return Date instance | | object | Object | Cast to Object | | string | String | Cast to String |

Custom casts

You can provide custom casts.

// main.js
import CastPropsMixin from 'vue-cast-props'

Vue.use(CastPropsMixin, {
  casts: {
    username: v => v.trim()
  }
})

// profile.vue
export default {
  props: {
    name: {
      cast: 'username'
    }
  }
}

<div>
  Username: {{ $c.name }}
</div>

API

vue-cast-props exposes the upcast api to the vue instance, so you can use your resources internally:

• type
• is
• to

type

• val: mixed The object to get the type of.

Get the type of an object.

Example:

vm.$cast.type([]); // 'array'
vm.$cast.type(true); // 'boolean'
vm.$cast.type(function () {}); // 'function'
vm.$cast.type(null); // 'null'
vm.$cast.type(123); // 'number'
vm.$cast.type({}); // 'object'
vm.$cast.type('foo'); // 'string'
vm.$cast.type(undefined); // 'undefined'

is

• val: mixed The object to check the type of.
• type: string The type to check for.

Check whether an object is of a given type. This accepts two arguments:

Example:

vm.$cast.is('foo', 'string'); // true
vm.$cast.is(123, 'string'); // false

vm.$cast.is([], 'array'); // true
vm.$cast.is([], 'object'); // false

vm.$cast.is(null, 'null'); // true
vm.$cast.is(null, 'object'); // false

to

• val: mixed The object to convert.
• type: string The type to convert to

Convert an object to a specific type. This accepts two arguments.

The way types are converted aims to be sensible and allow easy switching back-and-forth of common types. For example, switching between strings and arrays is quite fluid:

Example:

vm.$cast.to('foo', 'array'); // ['f', 'o', 'o']
vm.$cast.to(['f', 'o', 'o'], 'string'); // 'foo'

You can use type aliases with this function. The examples below illustrate the way types are converted.

Converting to an array

Converting to an array from a boolean, function, number or object simply wraps the value in an array:

Example:

vm.$cast.to(123, 'array'); // [123]

Strings are handled differently, an array is returned with each character in the string as an item:

Example:

vm.$cast.to('foo', 'array'); // ['f', 'o', 'o']

Null and undefined are converted to an empty array:

Example:

vm.$cast.to(null, 'array'); // []

Converting to a boolean

Boolean conversion simply converts to true or false based on whether the value is truthy or not. The only case where this doesn't follow JavaScript's standard behaviour is with empty arrays which are converted to false:

Example:

vm.$cast.to([1, 2, 3], 'boolean') // true
vm.$cast.to([], 'boolean') // false

Converting to a function

When converting to a function, the original value is simply wrapped in a new function. This function returns the original value:

Example:

vm.$cast.to('foo', 'function'); // function () { return 'foo'; }

Converting to null

As expected, converting to null will always return null:

Example:

vm.$cast.to('foo', 'null'); // null

Converting to a number

Converting to a number from a boolean, function, null or object simply calls Number with the original value as an argument, returning the expected value:

Example:

vm.$cast.to('true', 'number'); // 1

Arrays and strings are handled differently, an array is joined to create a string, then evaluated with parseInt; strings are simply evaluated with parseInt:

Example:

vm.$cast.to([1, 2, 3], 'number'); // 123
vm.$cast.to('123', 'number'); // 123
vm.$cast.to('foo', 'number'); // 0

Undefined is converted to 0 rather than NaN:

Example:

vm.$cast.to(undefined, 'number'); // 0

Converting to an object

Converting to an object simply calls Object with the value as a first argument. The following are equivalent:

Example:

vm.$cast.to('foo', 'object');
Object('foo');

Converting to a string

Converting to a string from a boolean, function, number or object simply returns the value added to an empty string, using JavaScript's default type conversion:

Example:

vm.$cast.to(true, 'string'); // 'true'
vm.$cast.to(123, 'string'); // '123'

Arrays are handled differently, they are joined with an empty string:

Example:

vm.$cast.to(['f', 'o', 'o'], 'string'); // 'foo'

Null and undefined are converted to an empty string rather than 'null' and 'undefined':

Example:

vm.$cast.to(null, 'string'); // ''

Converting to undefined

As expected, converting to undefined will always return undefined:

Example:

vm.$cast.to('foo', 'undefined'); // undefined

See the full documentation here...

License

MIT