Salted fish front end-js event capture / bubbling
Event bubbling
Event bubbling: multiple elements are nested in a hierarchical relationship, and these elements register the same event. After the event of the element inside starts, the event of the element outside also automatically triggers.
E.g:
<!DOCTYPE html>
<html>
<head>
<title>冒泡车测试</title>
<style type="text/css">
#bx1 {
width: 400px;
height: 400px;
background-color: red;
}
#bx2 {
width: 300px;
height: 300px;
background-color: blue;
}
#bx3 {
width: 200px;
height: 200px;
background-color: yellow;
}
</style>
</head>
<div id="bx1">
<div id="bx2">
<div id="bx3"></div>
</div>
</div>
<script>
var xy$ = function (id) {
return document.getElementById(id)
}
xy$("bx1").onclick = function () {
console.log(this.id)
}
xy$("bx2").onclick = function () {
console.log(this.id)
}
xy$("bx3").onclick = function () {
console.log(this.id)
}
</script>
</body>
</html>
Click bx3, both bx1 and bx2 have effect
Stop the event from bubbling
Stop event bubbling method
window.event.cancelBubble=true;//谷歌,IE8支持,火狐不支持
e.stopPropagation();//谷歌和火狐支持
and e are window.event event parameter object, is a standard IE, Firefox is a standard
event parameter e in IE8 browser is not present, then instead of using window.event
The above example can become like this: to save space only write JS part
//阻止事件冒泡函数
function stopBubble(e) {
if (e && e.stopPropagation)
e.stopPropagation()
else
window.event.cancelBubble = true
}
var xy$ = function (id) {
return document.getElementById(id)
};
xy$("bx1").onclick = function () {
console.log(this.id)
};
xy$("bx2").onclick = function () {
console.log(this.id)
};
xy$("bx3").onclick = function (e) {
console.log(this.id);
stopBubble(e)
}
effect
Event phase
1. Event capture phase: from outside to inside
2. Event target phase: the one selected
3. Event bubbling phase: from inside to outside
e.eventPhaseThe current stage of event propagation is returned through this property
* If the value of this property is:
* 1 ----> Capture stage
* 2 ----> Target stage
* 3 ----> Bubbling
*
var xy$ = function (id) {
return document.getElementById(id)
};
var objs = [xy$("bx3"), xy$("bx2"), xy$("bx1")];
//遍历注册事件
objs.forEach(function (ele) {
//为每个元素绑定事件
ele.addEventListener("click", function (e) {
console.log(this.id + "：" + e.eventPhase);
}, false);
});
