ADD dropdown menu component

src/app/ui/dropdown.js

+var yo = require('yo-yo')
+var csjs = require('csjs-inject')
+var EventManager = require('ethereum-remix').lib.EventManager
+
+var css = csjs`
+  .dropdown           {
+    position          : relative;
+    display           : flex;
+    flex-direction    : column;
+    color : black;
+  }
+  .selectbox          {
+    display           : flex;
+    align-items       : center;
+    background-color  : lightgrey;
+    border-radius     : 5px;
+    margin            : 3px;
+    cursor            : pointer;
+  }
+  .selected           {
+    display           : inline-block;
+    min-width         : 30ch;
+    max-width         : 30ch;
+    white-space       : nowrap;
+    text-overflow     : ellipsis;
+    overflow          : hidden;
+  }
+  .icon               {
+    padding           : 0px 5px;
+  }
+  .options            {
+    position          : absolute;
+    display           : flex;
+    flex-direction    : column;
+    min-width         : 30ch;
+    max-width         : 30ch;
+    top               : 21px;
+    left              : 10px;
+    background-color  : white;
+    border            : 1px solid black;
+  }
+  .option {
+    margin: 0;
+  }
+`
+/* USAGE:
+
+  var dropdown = new Dropdown({
+    options: [
+      'knownTransaction',
+      'unknownTransaction',
+      'log',
+      'info',
+      'error'
+    ],
+    defaults: ['knownTransaction']
+  })
+  dropdown.event.register('deselect', function (label) { })
+  dropdown.event.register('select', function (label) { })
+
+*/
+class Dropdown {
+  constructor (opts = {}) {
+    var self = this
+    self.event = new EventManager()
+    self.data = {
+      _options: opts.options || ['script'],
+      selected: opts.defaults || []
+    }
+    if (self.data._options.indexOf('script') !== -1) {
+      if (!opts.defaults) self.data.selected.push('script')
+    }
+    self._view = {}
+    self._api = opts.api
+    self._events = opts.events
+  }
+  render () {
+    var self = this
+    if (self._view.el) return self._view.el
+    self._view.selected = yo`
+      <div class=${css.selectbox}>
+        <span class=${css.selected}> [${self.data.selected.length}] ${self.data.selected.join(', ')}</span>
+        <i class="${css.icon} fa fa-caret-down"></i>
+      </div>
+    `
+    self._view.el = yo`
+      <div class=${css.dropdown} onclick=${show}>
+        ${self._view.selected}
+        <div class=${css.options} style="display: none;">
+          ${self.data._options.map(label => {
+            var input = yo`<input onchange=${emit} type="checkbox" />`
+            if (self.data.selected.indexOf(label) !== -1) {
+              input.checked = true
+              self.event.trigger('select', [label])
+            }
+            return yo`
+              <div class=${css.option}>
+                ${input}
+                <label>${label}</label>
+              </div>
+            `
+          })}
+        </div>
+      </div>
+    `
+    return self._view.el
+    function emit (event) {
+      var input = event.currentTarget
+      var label = input.nextSibling.innerText
+      if (input.checked) {
+        self.data.selected.push(label)
+        self.event.trigger('select', [label])
+      } else {
+        var idx = self.data.selected.indexOf(label)
+        self.data.selected.splice(idx, 1)
+        self.event.trigger('deselect', [label])
+      }
+      self._view.selected.children[0].innerText = `[${self.data.selected.length}] ${self.data.selected.join(', ')}`
+    }
+    function show (event) {
+      event.stopPropagation()
+      var options = event.currentTarget.children[1]
+      var parent = event.target.parentElement
+      var isOption = parent === options || parent.parentElement === options
+      if (isOption) return
+      if (options.style.display === 'none') {
+        options.style.display = ''
+        document.body.addEventListener('click', handler)
+      } else {
+        options.style.display = 'none'
+        document.body.removeEventListener('click', handler)
+      }
+      function handler (event) {
+        options.style.display = 'none'
+        document.body.removeEventListener('click', handler)
+      }
+    }
+  }
+}
+
+module.exports = Dropdown