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JavaScript JavaScript and the DOM (Retiring) Responding to User Interaction Event Bubbling and Delegation

Posted by vamosrope14
vamosrope14
14,932 Points

Need clarification on event bubbling

.

1 Answer

Brendan Whiting
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Brendan Whiting
Front End Web Development Techdegree Graduate 84,736 Points
Brendan Whiting
.a{fill-rule:evenodd;}techdegree seal-36
Brendan Whiting
Front End Web Development Techdegree Graduate 84,736 Points

A parent/ancestor element doesn't know how to apply that element to its children unless you explicitly give it instructions, and those instructions are defined in the function you pass as the callback in the event handler. 

<div id="parent">
  <div>child 1</div>
  <div>child 2</div>
  <div>child 3</div>
</div>

const parent = document.getElementById("parent");
parent.addEventListener("click", function() {
  const children = parent.querySelectorAll("div");  
  for (child of children) {
    child.style.color = "red";
  }
})

In this example, whichever child you click, the event will bubble up to the parent. And the parents instructions is to set ALL the children's text color to red, regardless of which one was clicked, because those are the instructions that I gave it in my event handler.