A simple mvvm

MVVM.js

class Register {
  constructor() {
    this.routes = []
  }

  regist(obj, k, fn) {
    const _i = this.routes.find(function(el) {
      if((el.key === k || el.key.toString() === k.toString()) 
        && Object.is(el.obj, obj)) {
        return el
      }
    })
    if(_i) {
      _i.fn.push(fn)
    } else {
      this.routes.push({
        obj: obj,
        key: k,
        fn: [fn]
      })
    }
  }

  build() {
    this.routes.forEach((route) => {
      observer(route.obj, route.key, route.fn)
    })
  }
}

class Parser {
  constructor(el, data, elist) {
    this._data = data
    this.$register = new Register()
    this.$el = document.querySelector(el)
    this.$elist = elist
    this.$frag = this.node2Fragment(this.$el)
    this.scan(this.$frag)
    this.$el.appendChild(this.$frag)
    this.$register.build()
  }

  node2Fragment(el) {
    const fragment = document.createDocumentFragment()
    let child = el.firstChild
    while(child) {
      fragment.appendChild(child)
      child = el.firstChild
    }
    return fragment
  }

  scan(node) {
    if(node === this.$frag || !node.getAttribute('data-list')) {
      for(let i = 0; i < node.children.length; i++) {
        const _thisNode = node.children[i]
        if(node.path) {
          _thisNode.path = node.path
        }
        this.parseEvent(_thisNode)
        this.parseClass(_thisNode)
        this.parseModel(_thisNode)
        if(_thisNode.children.length) {
          this.scan(_thisNode)
        }
      }
    } else {
      this.parseList(node)
    }
  }
  
  parseData(str, node) {
    const _list = str.split(':')
    let _data,
      _path,
      _j = 1
    let p = []
    _list.forEach((key, index) => {
      if(index === 0) {
        _data = this._data[key]
        p.push(key)
      } else {
        if(node.path) {
          _path = node.path[_j++]
          if(_path === key) {
            _data = _data[key]
          } else {
            p.push(_path)
            _data = _data[_path][key]
            _j++
          }
        } else {
          _data = _data[key]
        }
        p.push(key)
      }
    })
    if(node.path && node.path.length > p.length) {
      const _i = node.path[node.path.length - 1]
      if(typeof _i !== 'number') {
        return
      }
      _data = _data[_i]
      p.push(_i)
    }
    if(!node.path || node.path !== p) {
      node.path = p
    }
    return {
      path: p,
      data: _data
    }
  }
  
  parseEvent(node) {
    if(node.getAttribute('data-event')) {
      const eventName = node.getAttribute('data-event')
      const _type = this.$elist[eventName].type
      const _fn = this.$elist[eventName].fn.bind(node)
      if(_type === 'input') {
        let cmp = false
        node.addEventListener('compositionstart', function() {
          cmp = true
        })
        node.addEventListener('compositionend', function() {
          cmp = false
          node.dispatchEvent(new Event('input'))
        })
        node.addEventListener('input', function(){
          if(!cmp) {
            let start = this.selectionStart
            let end = this.selectionEnd
            _fn()
            this.setSelectionRange(start, end)
          }
        })
      } else {
        node.addEventListener(_type, _fn)
      }
    }
  }

  parseClass(node) {
    if(node.getAttribute('data-class')) {
      const className = node.getAttribute('data-class')
      const _data = this.parseData(className, node)
      if(!node.classList.contains(_data.data)) {
        node.classList.add(_data.data)
      }
      this.$register.regist(this._data, _data.path, function(old, now) {
        node.classList.remove(old)
        node.classList.add(now)
      })
    }
  }

  parseModel(node) {
    if(node.getAttribute('data-model')) {
      const modelName = node.getAttribute('data-model')
      const _data = this.parseData(modelName, node)
      if(node.tagName === 'INPUT') {
        node.value = _data.data
      } else {
        node.innerText = _data.data
      }
      this.$register.regist(this._data, _data.path, function(old, now) {
        if(node.tagName === 'INPUT') {
          node.value = now
        } else {
          node.innerText = now
        }
      })
    }
  }

  parseList(node) {
    const _item = this.parseListItem(node)
    const _list = node.getAttribute('data-list')
    const _listData = this.parseData(_list, node)
    _listData.data.forEach((_dataItem, index) => {
      const _copyItem = _item.cloneNode(true)
      if(node.path) {
        _copyItem.path = node.path.slice()
      }
      if(!_copyItem.path) {
        _copyItem.path = []
      }
      _copyItem.path.push(index)
      this.scan(_copyItem)
      node.insertBefore(_copyItem, _item)
    })
    node.removeChild(_item)
    this.$register.regist(this._data, _listData.path, () => {
      while(node.firstChild) {
        node.removeChild(node.firstChild)
      }
      const _listData = this.parseData(_list, node)
      node.appendChild(_item)
      _listData.data.forEach((_dataItem, index) => {
        const _copyItem = _item.cloneNode(true)
        if(node.path) {
          _copyItem.path = node.path.slice()
        }
        if(!_copyItem.path) {
          _copyItem.path = []
        }
        _copyItem.path.push(index)
        this.scan(_copyItem)
        node.insertBefore(_copyItem, _item)
      })
      node.removeChild(_item)
    })
  }

  parseListItem(node) {
    const me = this
    let target
    !function getItem(node) {
      for(let i = 0; i < node.children.length; i++) {
        const _thisNode = node.children[i]
        if(node.path) {
          _thisNode.path = node.path.slice()
        }
        me.parseEvent(_thisNode)
        me.parseClass(_thisNode)
        me.parseModel(_thisNode)
        if(_thisNode.getAttribute('data-list-item')) {
          target = _thisNode
        } else {
          getItem(_thisNode)
        } 
      }
    }(node)
    return target
  }
}

function observer(obj, k, callback) {
  if(Object.prototype.toString.call(k) === '[object Array]') {
    observePath(obj, k, callback)
  } else {
    let old = obj[k]
    if(Object.prototype.toString.call(old) === '[object Array]') {
      observeArray(old, callback)
    } else if (old.toString() === '[object Object]') {
      observeAllKey(old, callback)
    } else {
      Object.defineProperty(obj, k, {
        enumerable: true,
        configurable: true,
        get: function() {
          return old
        },
        set: function(now) {
          if(now !== old) {
            callback.forEach((fn) => {
              fn(old, now)
            })
          }
          old = now
        }
      })
    }
  }
}

function observePath(obj, path, callback) {
  let _path = obj
  let _key
  path.forEach((p, index) => {
    if(parseInt(p) === p) {
      p = parseInt(p)
    }
    if(index < path.length - 1) {
      _path = _path[p]
    } else {
      _key = p
    }
  })
  observer(_path, _key, callback)
}

function observeArray(arr, callback) {
  const oam = ['push', 'pop', 'shift', 'unshift', 'splice', 'sort', 'reverse']
  const arrayProto = Array.prototype
  const hackProto = Object.create(Array.prototype)
  oam.forEach(function(method){
    Object.defineProperty(hackProto, method, {
      writable: true,
      enumerable: true,
      configurable: true,
      value: function(...arg) {
        let old = arr.slice()
        let now = arrayProto[method].call(this, ...arg)
        callback.forEach((fn) => {
          fn(old, this, ...arg)
        })
        return now
      },
    })
  })
  arr.__proto__ = hackProto
}

function observeAllKey(obj, callback) {
  Object.keys(obj).forEach(function(key){
    observer(obj, key, callback)
  })
}

node.addEventListener('input', function(){ if(!cmp) { let start = this.selectionStart let end = this.selectionEnd _fn() this.setSelectionRange(start, end) } })

129行，这里使用setSelectionRange做了什么呢？