如何检查浏览器是否支持Polymer？

Question

我如何检查当前浏览器是否支持Polymer（JS或HTML代码）？

- Cody Weaver

Answer 1

简短回答：

快速测试：Firefox 38.0.5 显示 "No"，而 Chrome 44.0.2403.130 m 显示 "Yes"

function supportsPolymer() {
  return 'content' in document.createElement('template') && 'import' in document.createElement('link') && 'registerElement' in document && document.head.createShadowRoot;
}

if(supportsPolymer()) {
  
  //Good to go
  alert("Yes");
  
} else {
  
  //Is not supported
  alert("No");
  
}

详细答案：

您需要查看Polymer网站上的此列表。

• 模板
• HTML导入
• 自定义元素
• 影子DOM

必须支持这些特性：

• http://www.html5rocks.com/en/tutorials/webcomponents/template/

function supportsTemplate() {
  return 'content' in document.createElement('template');
}

if (supportsTemplate()) {
  // Good to go!
} else {
  // Use old templating techniques or libraries.
}

---

• https://www.polymer-project.org/0.5/platform/html-imports.html

function supportsImports() {
  return 'import' in document.createElement('link');
}

if (supportsImports()) {
  // Good to go!
} else {
  // Use other libraries/require systems to load files.
}

---

• https://www.polymer-project.org/0.5/platform/custom-elements.html

function supportsCustomElements() {
  return 'registerElement' in document;
}

if (supportsCustomElements()) {
  // Good to go!
} else {
  // Use other libraries to create components.
}

---

• https://www.polymer-project.org/0.5/platform/shadow-dom.html

如何检查浏览器是否支持影子DOM

if(document.head.createShadowRoot) {
    // I can shadow DOM
} else {
    // I can't
}

在一个函数中：

 function supportsShadowDom() {
   return document.head.createShadowRoot;
 }

以下是类似之前代码片段的未经测试版本：

 function supportsShadowDom() {
   return 'createShadowRoot' in document;
 }

好的，在实现所有可用函数后，你可以像这样做：

 if (supportsCustomElements() && supportsTemplate() && supportsImports() && supportsShadowDom()) {
   // Good to go!
 } else {
   // Use other libraries to create components.
 }

这是来自https://github.com/WebComponents/webcomponentsjs#browser-support的当前矩阵：

<table><thead>
<tr>
<th>Polyfill</th>
<th align="center">IE10</th>
<th align="center">IE11+</th>
<th align="center">Chrome*</th>
<th align="center">Firefox*</th>
<th align="center">Safari 7+*</th>
<th align="center">Chrome Android*</th>
<th align="center">Mobile Safari*</th>
</tr>
</thead><tbody>
<tr>
<td>Custom Elements</td>
<td align="center">~</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
</tr>
<tr>
<td>HTML Imports</td>
<td align="center">~</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
</tr>
<tr>
<td>Shadow DOM</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
</tr>
<tr>
<td>Templates</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
<td align="center">✓</td>
</tr>
</tbody></table>

这也许会很有趣： https://github.com/webcomponents/webcomponentsjs/issues/26

- OddDev