Onclick 使用 Javascript 将图标旋转 180 度

Question

I am needed to select all three icons and be able to have them rotate 180 when a user clicks on them. With the current code written, it is only targeting the first arrow icon, allowing it to turn 180 and back. Yet when I click on the other two icons, they do not rotate/ AND the first icon rotates even though I didn't click on the first icon.

 const arrowFlip = () => { let div = document.getElementById("nav__links"); let icon = document.getElementById("icon"); let open = false; div.addEventListener("click", function() { if (open) { icon.className = "menu-arrow-down"; } else { icon.className = "menu-arrow-down open"; } open =;open; }); }; arrowFlip();

 .menu-arrow-down { transform: rotate(0deg); transition: 1s linear; }.menu-arrow-down.open { transform: rotate(180deg); transition: 1s linear; }

 <ul id="nav__links" class="nav__links"> <div class="desktop__nav"> <li class="parent"> <a href="#">Product</a> <img id="icon" class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Overview</li> <li>Pricing</li> <li>Marketplace</li> <li>Features</li> <li>Integrations</li> </ul> </li> <li class="parent"> <a href="#">Company</a> <img id="icon" class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>About</li> <li>Team</li> <li>Blog</li> <li>Careers</li> </ul> </li> <li class="parent"> <a href="#">Connect</a> <img id="icon" class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Contact</li> <li>Newsletter</li> <li>LinkedIn</li> </ul> </li> </div>

Answer 1

IDs need to be unique.

Delegate the click - it is much simpler

 document.getElementById("nav__links").addEventListener("click", function(e) { const tgt = e.target; if (tgt.classList.contains('menu-arrow-down')) { // make sure we only target elements with this class tgt.classList.toggle('open'); // here you can test tgt.classList.contains('open') to see the state } });

 .menu-arrow-down { transform: rotate(0deg); transition: 1s linear; }.menu-arrow-down.open { transform: rotate(180deg); transition: 1s linear; }

 <ul id="nav__links" class="nav__links"> <div class="desktop__nav"> <li class="parent"> <a href="#">Product</a> <img class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Overview</li> <li>Pricing</li> <li>Marketplace</li> <li>Features</li> <li>Integrations</li> </ul> </li> <li class="parent"> <a href="#">Company</a> <img class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>About</li> <li>Team</li> <li>Blog</li> <li>Careers</li> </ul> </li> <li class="parent"> <a href="#">Connect</a> <img class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Contact</li> <li>Newsletter</li> <li>LinkedIn</li> </ul> </li> </div>

Answer 2

You can add event listeners to all arrows, that way you won't need an id:

 let allArrows = document.querySelectorAll(".menu-arrow"); allArrows.forEach(arrow => { arrow.addEventListener('click', function() { this.className = this.className === "menu-arrow-down open"? "menu-arrow-down": "menu-arrow-down open"; }); });

 .menu-arrow-down { transform: rotate(0deg); transition: 1s linear; }.menu-arrow-down.open { transform: rotate(180deg); transition: 1s linear; }

 <ul id="nav__links" class="nav__links"> <div class="desktop__nav"> <li class="parent"> <a href="#">Product</a> <img id="icon" class="menu-arrow menu-arrow-down" src="https://placekitten.com/50/50" alt="arrow" /> <ul class="sub-menu"> <li>Overview</li> <li>Pricing</li> <li>Marketplace</li> <li>Features</li> <li>Integrations</li> </ul> </li> <li class="parent"> <a href="#">Company</a> <img id="icon" class="menu-arrow menu-arrow-down" src="https://placekitten.com/50/50" alt="arrow" /> <ul class="sub-menu"> <li>About</li> <li>Team</li> <li>Blog</li> <li>Careers</li> </ul> </li> <li class="parent"> <a href="#">Connect</a> <img id="icon" class="menu-arrow menu-arrow-down" src="https://placekitten.com/50/50" alt="arrow" /> <ul class="sub-menu"> <li>Contact</li> <li>Newsletter</li> <li>LinkedIn</li> </ul> </li> </div>

Answer 3

Like the others wrote: an id has to be unique. Furthermore you don't need it since you simply can use the target of the event and toggle its class .open if it has the class menu-arrow .

 document.getElementById("nav__links").addEventListener("click", function(event) { if (event.target.className.includes('menu-arrow')) { event.target.classList.toggle('open'); } });

 .menu-arrow-down { transform: rotate(0deg); transition: 1s linear; }.menu-arrow-down.open { transform: rotate(180deg); transition: 1s linear; }

 <ul id="nav__links" class="nav__links"> <div class="desktop__nav"> <li class="parent"> <a href="#">Product</a> <img class="menu-arrow menu-arrow-down" src="https://via.placeholder.com/160x120" alt="arrow" /> <ul class="sub-menu"> <li>Overview</li> <li>Pricing</li> <li>Marketplace</li> <li>Features</li> <li>Integrations</li> </ul> </li> <li class="parent"> <a href="#">Company</a> <img class="menu-arrow menu-arrow-down" src="https://via.placeholder.com/160x120" alt="arrow" /> <ul class="sub-menu"> <li>About</li> <li>Team</li> <li>Blog</li> <li>Careers</li> </ul> </li> <li class="parent"> <a href="#">Connect</a> <img class="menu-arrow menu-arrow-down" src="https://via.placeholder.com/160x120" alt="arrow" /> <ul class="sub-menu"> <li>Contact</li> <li>Newsletter</li> <li>LinkedIn</li> </ul> </li> </div>

Answer 4

This is because the id attribute is unique and cannot be used with multiple elements. getElementById will return the first element with the id of icon , producing the result you are seeing. To fix, I suggest passing a parameter to your function, whether it's an event or simply a number. In this example, I'll use a number:

 let open = false; const arrowFlip = (number) => { let icon = document.getElementsByClassName("icon")[number]; if (open) { icon.className = "icon menu-arrow-down"; } else { icon.className = "icon menu-arrow-down open"; } open =;open; };

 .menu-arrow-down { transform: rotate(0deg); transition: 1s linear; }.menu-arrow-down.open { transform: rotate(180deg); transition: 1s linear; }

 <ul id="nav__links" class="nav__links"> <div class="desktop__nav"> <li class="parent"> <a href="#">Product</a> <img class="icon" onclick="arrowFlip(0)" class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Overview</li> <li>Pricing</li> <li>Marketplace</li> <li>Features</li> <li>Integrations</li> </ul> </li> <li class="parent"> <a href="#">Company</a> <img class="icon" onclick="arrowFlip(1)"class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>About</li> <li>Team</li> <li>Blog</li> <li>Careers</li> </ul> </li> <li class="parent"> <a href="#">Connect</a> <img class="icon" onclick="arrowFlip(2)"class="menu-arrow menu-arrow-down" src="./images/icon-arrow-light.svg" alt="arrow" /> <ul class="sub-menu"> <li>Contact</li> <li>Newsletter</li> <li>LinkedIn</li> </ul> </li> </div>

The onclick() on each image will trigger this function, sending a number parameter, allowing the correct arrow to be referenced. Then, when it flips, the code will know what image the user is referencing to.