git ssb

1
var isObservable = require('../is-observable')
2
var Set = require('../set')
3
var watch = require('../watch')
4
5
module.exports = applyProperties
6
7
function applyProperties (target, properties, data) {
8
  var classList = Set()
9
  if (target.className) {
10
    classList.add(target.className)
11
  }
12
13
  for (var key in properties) {
14
    var valueOrObs = properties[key]
15
16
    if (key === 'style') {
17
      // TODO: handle observable at root for style objects
18
      var value = resolve(valueOrObs)
19
      for (var k in value) {
20
        var styleObs = isObservable(value[k]) ? value[k] : null
21
        if (styleObs) {
22
          data.bindings.push(new Binding(bindStyle, target, styleObs, k))
23
        } else {
24
          target.style.setProperty(k, value[k])
25
        }
26
      }
27
    } else if (key === 'hooks') {
28
      var value = resolve(valueOrObs)
29
      if (Array.isArray(value)) {
30
        value.forEach(function (v) {
31
          data.bindings.push(new HookBinding(v, target))
32
        })
33
      }
34
    } else if (key === 'attributes') {
35
      var value = resolve(valueOrObs)
36
      for (var k in value) {
37
        var attrObs = isObservable(value[k]) ? value[k] : null
38
        if (attrObs) {
39
          data.bindings.push(new Binding(bindAttr, target, attrObs, k))
40
        } else {
41
          target.setAttribute(k, value[k])
42
        }
43
      }
44
    } else if (key === 'events') {
45
      for (var name in valueOrObs) {
46
        target.addEventListener(name, valueOrObs[name], false)
47
      }
48
    } else if (key.slice(0, 3) === 'ev-') {
49
      target.addEventListener(key.slice(3), valueOrObs, false)
50
    } else if (key === 'className' || key === 'classList') {
51
      if (Array.isArray(valueOrObs)) {
52
        valueOrObs.forEach(function (v) {
53
          classList.add(v)
54
        })
55
      } else {
56
        classList.add(valueOrObs)
57
      }
58
    } else {
59
      target[key] = resolve(valueOrObs)
60
      var obs = isObservable(valueOrObs) ? valueOrObs : null
61
      if (obs) {
62
        data.bindings.push(new Binding(bind, target, obs, key))
63
      }
64
    }
65
  }
66
67
  if (containsObservables(classList)) {
68
    data.bindings.push(new Binding(bindClassList, target, classList, 'className'))
69
  } else {
70
    // OPTIMISATION: no need to create a binding if the list is never going to change
71
    target.className = classList().join(' ')
72
  }
73
}
74
75
function containsObservables (obs) {
76
  for (var i = 0, len = obs.getLength(); i < len; i++) {
77
    if (isObservable(obs.get(i))) {
78
      return true
79
    }
80
  }
81
}
82
83
function bindClassList (target, obs, key) {
84
  return watch(obs, function boundClassList (value) {
85
    value = [].concat.apply([], value).filter(present).join(' ')
86
    if (value || target[key]) {
87
      target[key] = value
88
    }
89
  })
90
}
91
92
function bindStyle (target, styleObs, key) {
93
  return watch(styleObs, function boundStyle (value) {
94
    target.style.setProperty(key, value)
95
  })
96
}
97
98
function bindAttr (target, attrObs, key) {
99
  return watch(attrObs, function boundAttr (value) {
100
    if (value == null) {
101
      target.removeAttribute(key)
102
    } else {
103
      target.setAttribute(key, value)
104
    }
105
  })
106
}
107
108
function bind (target, obs, key) {
109
  return watch(obs, function bound (toValue) {
110
    var fromValue = target.getAttribute(key)
111
    if (fromValue !== toValue) {
112
      target.setAttribute(key, toValue)
113
    }
114
  })
115
}
116
117
function present (val) {
118
  return val != null
119
}
120
121
function resolve (source) {
122
  return typeof source === 'function' ? source() : source
123
}
124
125
function Binding (fn, element, source, key) {
126
  this.element = element
127
  this.source = source
128
  this.key = key
129
  this.fn = fn
130
  this.bound = false
131
}
132
133
Binding.prototype = {
134
  bind: function () {
135
    if (!this.bound) {
136
      this._release = this.fn(this.element, this.source, this.key)
137
      this.bound = true
138
    }
139
  },
140
  unbind: function () {
141
    if (this.bound) {
142
      this._release()
143
      this._release = null
144
      this.bound = false
145
    }
146
  }
147
}
148
149
function HookBinding (fn, element) {
150
  this.element = element
151
  this.fn = fn
152
  this.bound = false
153
}
154
155
HookBinding.prototype = {
156
  bind: function () {
157
    if (!this.bound) {
158
      this._release = this.fn(this.element)
159
      this.bound = true
160
    }
161
  },
162
  unbind: function () {
163
    if (this.bound && typeof this._release === 'function') {
164
      this._release()
165
      this._release = null
166
      this.bound = false
167
    }
168
  }
169
}
170