README.en.md

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smart-observe

smart-observe comes from Vue.js and is a small, efficient library for observing changes of javascript Object, Array and Class.

Installation

npm install --save smart-observe

or

bower install --save smart-observe

Usage

To watch expression. observe.watch(target, expression, callback) or observe(target, expression, callback)

Try it on: codepen jsfiddle

const target = {a: 1}
observe(target, 'a', function (newValue, oldValue) {
  console.log(newValue, oldValue)
})
target.a = 3
// 3 1

To add computed property. observe.compute(target, name, getter)

Try it on: codepen jsfiddle

const target = {a: 1}
observe.compute(target, 'b', function () {
  return this.a * 2
})
console.log(target.b)
// 2
target.a = 3
console.log(target.b)
// 6

To watch expressions and computed properties. observe.react(options)

Try it on: codepen jsfiddle

const options = {
  data: {
    PI: Math.PI,
    radius: 1,
  },
  computed: {
    'area': function () {
      return this.PI * this.square(this.radius) // πr²
    },
  },
  watchers: {
    'area': function (newValue, oldValue) {
      console.log(`area: ${newValue}`)
    },
  },
  methods: {
    square (num) {
      return num * num
    },
  },
}
const target = observe.react(options)
target.radius = 3
// area: 28.274333882308138

API

properties

name	type	value	detail
observe.deep	boolean	The default is false	If true, observe.watch(target, expression, callback) will observe target deeply
observe.sync	boolean	The default is false	If true, observe.watch(target, expression, callback) will invoke callback immediately when a property change is detected
observe.default	function	Could only be one of observe.react, observe.watch and observe.compute. The default is observe.watch	Set actual method to observe.default for observe(...)

methods

observe(...)

• It's syntactic sugar of observe.default. See 'properties' for details

observe.watch(target, expression, callback)

• target: Any object
• expression: string or function
• callback: function
• Returns Watcher. And calling watcher.teardown() could unwatch expression

observe.compute(target, name, accessor, cache)

• target: Any object
• name: string
• accessor:
  • function: It will be the get of accessor
  • Object: Contains: (at least get or set)
    • get: function
    • set: function
    • cache: boolean. Optional. The default is true. If false, the get will be evaluated whenever reading computed properties
• cache: boolean. Same as accessor.cache

observe.react(options, target)

• options: Object. Contains:
  • data: It's the properties to add
  • computed: It's the computed properties to add
  • watchers: It's the watchers to watch properties or computed properties
  • methods: The methods to add. And these will bind to target
• target: Any object. Optional. The default is empty object. It will be attached with the fields of options
• returns target

License

MIT