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JavaScript DOM Scripting By Example Adding and Removing Names Practice with Function Scope

Posted by Anthony Smith
Anthony Smith
9,897 Points

How to alter the javascript code without adding any lines to the blue button's event handler?

Shouldn't this work? I am simply taking the code and using it in a if else statement. Although not specifically what the challenge asks for but I still think it should work this way if needed.

app.js 
const redButton = document.getElementById('redButton');
const blueButton = document.getElementById('blueButton');

redButton.addEventListener('click', (e) => {
  const colorSquare = document.getElementById('colorDiv');
  if (e.target.tagName === 'redButton') {
      colorSquare.style.backgroundColor = 'red';
      } else if (e.target.tagName === 'blueButton') {
        colorSquare.style.backgroundColor = 'blue';
      }
  });
style.css 
div {
  height: 50px;
  float: left;
  padding-top: 40px;
  padding-left: 20px;

}

#colorDiv {
  padding: 0;
  width: 100px;
  height: 100px;
  background-color: gray;
}

button {
  height: 30px;
  border-radius: 10px;
}
#redButton {
  background-color: #ff5959;
  border-color: red;
}

#blueButton {
  background-color: lightblue;
  border-color: #7C9EFC;
}

1 Answer

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

This doesn't work for the red button because "redButton" is being compared with the tagName when it is actually the id.

And it won't work on the blue button even after fixing the id reference because the handler is only being attached directly to the red button.

But you could make it a delegated handler for both by attaching it to a common parent (like the body) instead:

document.body.addEventListener("click", e => {
  const colorSquare = document.getElementById("colorDiv");
  if (e.target.id === "redButton") {
    colorSquare.style.backgroundColor = "red";
  } else if (e.target.id === "blueButton") {
    colorSquare.style.backgroundColor = "blue";
  }
});