如何將我的代碼應用於多個元素？

Question

下面的代碼有效，但是我想做的是應用於“工作2”。 我試過了：paras = Array.from（document.querySelectorAll（'。working1 .working2'））; 但這不起作用。

代碼背景：不斷循環所有元素，直到找到一個空元素。 一旦找到，它將用變量替換。 然后打破循環。

 paras = Array.from(document.querySelectorAll('.working1')); for(const para of paras) { if(para.innerHTML === '') { para.innerHTML = partnumber; } 

 <p id="machine1" class="working1"></p> <p id="machine2" class="working1"></p> <p id="machine3" class="working1"></p> <p id="machine4" class="working1"></p> <p id="machine5" class="working2"></p> <p id="machine6" class="working2"></p> <p id="machine7" class="working2"></p> <p id="machine8" class="working2"></p> 

Answer 1

querySelectorAll('.working1 .working2')將選擇的元件class = working2內部working1使用querySelectorAll('.working1, .working2') 。
請參閱一個規則上的選擇器組 。

 paras = Array.from(document.querySelectorAll('.working1,.working2')); let partnumber = 0 for(const para of paras) { partnumber++ if(para.innerHTML === '') { para.innerHTML = partnumber; } } 

 <p id="machine1" class="working1"></p> <p id="machine2" class="working1"></p> <p id="machine3" class="working1"></p> <p id="machine4" class="working1"></p> <p id="machine5" class="working2"></p> <p id="machine6" class="working2"></p> <p id="machine7" class="working2"></p> <p id="machine8" class="working2"></p> 

Answer 2

使用document.querySelectorAll（'p [class ^ =“ working”]'）

 paras = Array.from(document.querySelectorAll('p[class^="working"]')); let partnumber = 0 for(const para of paras) { partnumber++ if(para.innerHTML === '') { para.innerHTML = partnumber; } } 

 <p id="machine1" class="working1"></p> <p id="machine2" class="working1"></p> <p id="machine3" class="working1"></p> <p id="machine4" class="working1"></p> <p id="machine5" class="working2"></p> <p id="machine6" class="working2"></p> <p id="machine7" class="working2"></p> <p id="machine8" class="working2"></p>