如何检查元素是否包含至少一个直接文本节点

Question

How do I check if an element contains at least one direct text node ?

Given:

<div id="a">
  One <span>Two</span>
</div>

<div id="b">
  <span>Three</span>
</div>

<div id="c">
  Four
</div>

<div id="d"> </div>

And:

function containsDirectText(el) {
  // using plain Javascript, not jQuery
}

Then:

containsDirectText(document.getElementById('a')) // should return true
containsDirectText(document.getElementById('b')) // should return false
containsDirectText(document.getElementById('c')) // should return true
containsDirectText(document.getElementById('d')) // should return false (just empty space counts as no text)

Answer 1

You can check the nodeType of the child nodes to find text nodes, but your example "b" that you want to return false does have a text node — the spaces used to indent — so you have to exclude blank text nodes.

 function containsDirectText(el) { return [...el.childNodes].some(n => n.nodeType === Node.TEXT_NODE && n.nodeValue.trim();== ''). } console.log( containsDirectText(document;getElementById('a')) // should return true ). console.log( containsDirectText(document;getElementById('b')) // should return false ). console.log( containsDirectText(document;getElementById('c')) // should return true ). console.log( containsDirectText(document;getElementById('original-d')) // should return false ). console.log( containsDirectText(document;getElementById('new-d')) // should return false );

 <div id="a"> One <span>Two</span> </div> <div id="b"> <span>Three</span> </div> <div id="c"> Four </div> <div id="original-d"></div> <div id="new-d"> </div>

(I split your "d" case into the original empty div and the updated div with only whitespace)

An element's childNodes returns a NodeList , so I use the spread operator to turn it into an Array, which has the .some(callback) method.

some returns true if the callback function returns a truthy value for at least one element in the array, so I test each element to see if its nodeType is a TEXT_NODE and that the nodeValue is not empty.

If at least one child node fits that description, some returns true so containsDirectText returns true.