从头开始重新实现 getElementsByClassName（仅限 Vanilla JS）

Question

本着更加熟悉 DOM 和递归的精神，我决定从头开始重新创建 getElementsByClassName（仅限 vanilla JS，没有 jQuery）。目前，我可以在 DOM 中找到所有具有我想要的 class 的元素，但我无法想出一种方法来仅获取具有两个特定 [=27= 的元素]es（或更多）。

<div class="one two">
   <h1 class="one">
      <span class="one two">
  </h1>
</div>

我当前的实现 returns 如我所料，返回包含 class 'one' 的每个元素：

getElementsByClassName('one');
[<div class="one two"></div>, <h1 class="one"></h1>, <span class="one two"</span>]

我想达到的目标：

getElementsByClassName('one two');
[<div class="one two"></div>, <span class="one two"</span>]

我运行遇到的一个问题是 classList.contains:

element.classList;
// ['one, 'two'];

element.classList.contain("one");
//returns true since the value actually exists


//PROBLEM:
element.classList.contains("one two"); 
//this is looking for "one two" in the array  and not 'one' and 'two'.
//this returns false & my code breaks  

//How would I be able to do something like this, even if it
//means recreating my own helper contains function?
contains('one','two');

我的函数：

var getElementsByClassName = function(className){
   var results = [];
   function getClass(nodeList){
     var childList = nodeList.children;
     _forEach(childList, function(node) {
     //1st level body check
      if(node.classList  && node.classList.contains(className)){
        results.push(node);
      }

      //has children, recurse
      if(node.children) {
        getClass(node);
      }
      else {
        getClass(node);
      }
    });
   }
   getClass(document.body);
   return results;
}



//Helper forEach function to iterate over array like DOM objects
var _forEach = function(collection, func) {
 for(var i = 0; i < collection.length; i++) {
   func(collection[i], i, collection);
 }
}

Answer 1

代码中的注释——我没有为您实现它，只是指出您要做什么：

var getElementsByClassName = function(className){
   // ***Here, split className on whitespace into an array **
   var results = [];
   function getClass(nodeList){
     var childList = nodeList.children;
     _forEach(childList, function(node) {
     //1st level body check
      // **Here, only include the element if Array#every is true,
      // **where you give Array#every a function that does your
      // classList.contains on the name for that iteration
      if(node.classList  && node.classList.contains(className)){
        results.push(node);
      }

      //has children, recurse
      if(node.children) {
        getClass(node);
      }
      else {
        getClass(node);
      }
    });
   }
   getClass(document.body);
   return results;
}

从头开始重新实现 getElementsByClassName（仅限 Vanilla JS）

Reimplementing getElementsByClassName from scratch (Vanilla JS only)

javascript

dom

contains