在阅读了element.focus()
方法focus()
之后,我编写了以下代码来模糊在调用返回到事件循环之前由文档关注的元素。
我们的想法是,我们为每个元素添加一个焦点监听器,然后在 onload 之后移除焦点监听器,以便focus()
在用户事件之后调用的网站(例如 jsfiddle.com 或 Google 结果页面)在页面有之后仍然可以正常工作加载。
警告:我还无法弄清楚如何让 Chrome 禁用autofocus
字段。
内容脚本(称之为 unfocus.js):
document.addEventListener('DOMNodeInsertedIntoDocument', onInsertedIntoDocument, true);
document.addEventListener('DOMNodeRemovedFromDocument', onRemovedFromDocument, true);
window.addEventListener('load', function(e) {
setTimeout(function() {
removeOnFocus(document.documentElement);
document.removeEventListener('DOMNodeInsertedIntoDocument', onInsertedIntoDocument, true);
document.removeEventListener('DOMNodeRemovedFromDocument', onRemovedFromDocument, true);
}, 1);
}, false);
// Whenever an element is inserted into document, listen for
// simple event named 'focus'.
function onInsertedIntoDocument(e) {
var elt = e.target;
if (elt.nodeType === 1)
elt.addEventListener('focus', onfocus, false);
}
function onRemovedFromDocument(e) {
var elt = e.target;
if (elt.nodeType === 1)
removeOnFocus(elt);
}
function onfocus(e) {
// In Chrome, caller is null if the user initiated the focus,
// and non-null if the focus was caused by a call to element.focus().
var causedByUser = (onfocus.caller == null);
console.log('onfocus ' + e.target.nodeName +
': caused by user? ' +causedByUser +
(e.target.autofocus ? ' autofocus' : ''));
if (! causedByUser) {
e.target.blur();
}
}
// Clean up by removing all the 'focus' event listeners.
function removeOnFocus(elt) {
elt.removeEventListener('focus', onfocus, false);
for (var i = 0; i < elt.children.length; i++)
removeOnFocus(elt.children[i]);
}
而这个 manifest.json:
{
"name": "unfocus",
"version": "1.0",
"content_scripts": [
{
"matches": ["http://*/*"],
"js": ["unfocus.js"],
"run_at": "document_start"
}
]
}