Polymer

Components

  • AngularJS
  • React
  • Ember

Based on Web Components

Custom Elements

document.registerElement('x-foo', {
    prototype: Object.create(HTMLParagraphElement.prototype, {
        firstMember: {
            get: function() { return "foo"; },
            enumerable: true,
            configurable: true
        },
        // specify more members for your prototype.
        // ...
    }),
    extends: 'p'
});
<body>
    ...

    <x-foo></x-foo>

    ...
</body>

HTML Imports

<link rel="import" href="/imports/heart.html">

<template>

<template>
<style>
  :host {
    background: #f8f8f8;
    padding: 10px;
    transition: all 400ms ease-in-out;
    box-sizing: border-box;
    border-radius: 5px;
    width: 450px;
    max-width: 100%;
  } 
  :host(:hover) {
    background: #ccc;
  }
  div {
    position: relative;
  }
  header {
    padding: 5px;
    border-bottom: 1px solid #aaa;
  }
  h3 {
    margin: 0 !important;
  }
  textarea {
    font-family: inherit;
    width: 100%;
    height: 100px;
    box-sizing: border-box;
    border: 1px solid #aaa;
  }
  footer {
    position: absolute;
    bottom: 10px;
    right: 5px;
  }
</style>
<div>
  <header>
    <h3>Add a Comment</h3>
  </header>
  <content select="p"></content>
  <textarea></textarea>
  <footer>
    <button>Post</button>
  </footer>
</div>
</template>

<div id="host">
  <p>Instructions go here</p>
</div>

<script>
  var shadow = document.querySelector('#host').createShadowRoot();
  shadow.appendChild(document.querySelector('template').content);
</script>

Shadow DOM

<button>Hello, world!</button>
<script>
var host = document.querySelector('button');
var root = host.createShadowRoot();
root.textContent = 'こんにちは、影の世界!';
</script>

Polymer

Polymer 首先针对 Web Components 做了 polyfill,并将其进一步封装和增强,满足日常开发的习惯和需求。

<polymer-element name="custom-element">
    <template>
        <style>
            :host {
                ...
            }
        </style>
        <div>...</div>
    </template>
    <script>
        (function() {
            Polymer('custom-element', {
                onMenuSelect: function () {
                   ...
                }
            });
        })();
    </script>
</polymer-element>

5 mins to build an custom element ourselfs

Why Polymer?

encapsulation /inˌkæpsjuˈleiʃən/ 

AngularJS Directive 的标准化替代方案

New Problems with Polymer

  • Concat?
  • Dependency Management?
  • Project Structure?
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