javascript - 如何检查某个元素是否具有属性 "name"以某物开头，而不是 "value"

Question

我将使用以 “data-mo-” 开头的各种数据属性名称。

假设我有这些元素:

<span data-mo-top-fade-duration="600">Title 1</span>
<span data-mo-bottom-fade-duration="600">Title 2</span>
<span data-mo-right-fade-duration="600">Title 3</span>
<span data-mo-left-fade-duration="600">Title 4</span>

我知道如何处理数据属性值以某个值开始的元素，但是如何处理数据属性names？

Answer 1

如果您只想查找给定节点是否具有以特定字符串开头的属性，那么一种方法如下:

// node: a single HTMLELement node,
// attr: the string to test against the attribute names:
function hasAttributeStartingWith(node, attr) {

  // here we return the result, using Array.from() to turn
  // the node-map of attributes into an Array, and then
  // Array.prototype.filter() to remove any attributes that
  // do not return a true/truthy result against the supplied
  // assessment:
  return Array.from(node.attributes).filter(function(attributeNode) {
    // attributeNode: a reference to the current attribute-node
    // of the array of attribute-nodes over which we're iterating.

    // here we test to see if the nodeName (the attribute-name)
    // of the attribute-node begins with  the supplied string
    // (held in the 'attr' variable):
    return attributeNode.nodeName.indexOf(attr) === 0;

  // if the filtered array is greater than zero then
  // there are some attributes beginning with the
  // supplied string:
  }).length > 0;
}

// here we convert the nodeList returned from document.querySelectorAll()
// into an Array, using Array.from(), and iterate over those elements
// using Array.prototype.forEach():
Array.from(document.querySelectorAll('span')).forEach(function(span) {
  // 'span': a reference to the current <span> element of the
  // array of <span> elements over which we're iterating.

  // using the function within the 'if' assessment, since it
  // returns a Boolean true/false:
  if (hasAttributeStartingWith(span, 'data-mo')) {

    // using the Element.classList API to add
    // the 'hasAttributeStartingWith' class to
    // the current <span> if the function returns
    // true:
    span.classList.add('hasAttributeStartingWith');
  }

});

function hasAttributeStartingWith(node, attr) {
  return Array.from(node.attributes).filter(function(attributeNode) {
    return attributeNode.nodeName.indexOf(attr) === 0;
  }).length > 0;
}

Array.from(document.querySelectorAll('span')).forEach(function(span) {
  if (hasAttributeStartingWith(span, 'data-mo')) {
    span.classList.add('hasAttributeStartingWith');
  }
});

.hasAttributeStartingWith {
  display: inline-block;
  font-size: 1.5em;
  color: limegreen;
}

<span data-mo-top-fade-duration="600">Title 1</span>
<span data-mo-bottom-fade-duration="600">Title 2</span>
<span data-mo-right-fade-duration="600">Title 3</span>
<span data-mo-left-fade-duration="600">Title 4</span>

JS Fiddle demo .

在上面所有元素都有一个以data-mo开头的属性，为了更具体地展示它的工作原理，请尝试:

Array.from(document.querySelectorAll('span')).forEach(function(span) {
  if (hasAttributeStartingWith(span, 'data-mo-b')) {
    span.classList.add('hasAttributeStartingWith');
  }
});

function hasAttributeStartingWith(node, attr) {
  return Array.from(node.attributes).filter(function(attributeNode) {
    return attributeNode.nodeName.indexOf(attr) === 0;
  }).length > 0;
}

Array.from(document.querySelectorAll('span')).forEach(function(span) {
  if (hasAttributeStartingWith(span, 'data-mo-b')) {
    span.classList.add('hasAttributeStartingWith');
  }
});

.hasAttributeStartingWith {
  display: inline-block;
  font-size: 1.5em;
  color: limegreen;
}

<span data-mo-top-fade-duration="600">Title 1</span>
<span data-mo-bottom-fade-duration="600">Title 2</span>
<span data-mo-right-fade-duration="600">Title 3</span>
<span data-mo-left-fade-duration="600">Title 4</span>

JS Fiddle demo .

这应该只匹配具有以字符串 data-mo-b 开头的属性的元素，仅第二个样式 <span>元素。

引用资料:

• > Array.from() .
• > Array.prototype.filter() .
• > Array.prototype.forEach() .
• > document.querySelectorAll() .
• > Element.attributes .
• > Element.classList API .
• > Node.nodeName .
• > String.prototype.indexOf() .