Package Exports
- static-props
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Readme
static-props
defines static object attributes using
Object.defineProperties
Table Of Contents:
Installation
With npm do
npm install static-props --save
Usage
Let's create a classic Point2d class and add constant attributes.
'use strict'
var staticProps = require('static-props')
class Point2d {
constructor (x, y, label) {
// Suppose you have few static attributes in your class.
const color = 'red'
// Add constant attributes quickly.
staticProps(this)({label, color})
// Add enumerable attributes.
var enumerable = true
staticProps(this)({x, y}, enumerable)
}
}
After instantiating the class, we can check that its props cannot be changed.
var p = new Point2d(1, 2)
// Trying to modify a static prop will throw as you expect.
p.label = 'B'
// TypeError: Cannot assign to read only property 'label' of #<Point2d>
Attributes x
, y
were configured to be enumerable
console.log(p) // Point2d { x: 1, y: 2 }
If you want to add a static attribute class, you can also do
staticProps(Point2d)({ dim: 2 })
so you can access it with
console.log(Point2d.dim) // 2
Annotated source
API is staticProps(obj)(props[, enumerable])
/**
* @param {Object} obj
* @returns {Function}
*/
function staticProps (obj) {
/**
* @param {Object} props
* @param {Boolean} [enumerable]
*/
return function (props, enumerable) {
Since static
is a reserved keywork, let's use statik
var statik = {}
Add every prop to obj as not writable nor configurable, i.e. static
for (var propName in props) {
var propValue = props[propName]
statik[propName] = {
value: propValue,
configurable: false,
enumerable: enumerable,
writable: false
}
}
Object.defineProperties(obj, statik)
}
}
Export function
module.exports = staticProps