end method in jquery

jQuery is a very popular JavaScript library that simplifies JavaScript programming and has become one of the essential tools in front-end development. In jQuery, chain operations are often used to operate on DOM elements. The end() method in chain operations is a commonly used method, which is used to roll back to the previous state.

end()The method is used to reset the currently selected collection to its previous state. That is, if multiple operations are performed on a selection set, the end() method can be used to return to the previous selection set.

In jQuery, the end() method can be used anywhere in the chain operation. When you need to go back to the previous state in a chain operation, you only need to call the end() method.

For example, we have an HTML structure as follows:

<div class="parent">
  <div class="child">child 1</div>
  <div class="child">child 2</div>
</div>

We can use the following code to set all child elements to red and return it to the parent element:

$(".parent").children().css("color", "red").end();

When When we call the end() method, it will fall back to the state where the selector selects the .parent element, that is, the selection collection is reset and no longer affects .child element.

In addition to using the end() method in chain operations, it can also be used in other scenarios. For example, when getting and setting properties, the end() method can be used to fall back to the original selection set. Here's an example of getting an element's attributes and returning them to their previous state:

$(".test")
  .attr("name", "test")
  .end()
  .attr("id", "test");

In this example, we set an element named test on the .test element attributes. Then use the end() method to return to the original selection set, which is the set state that acts on the .test element. Then we use the attr() method to set the id attribute, but this attribute will not be applied to the .test element, but to the element before selecting the collection. element because we have used the end() method to fall back to the original selection set.

Finally, it should be noted that the end() method can only be used for the collection returned by the previous step in the chain operation. If other operations are used in the chain operation, the end() method will have no effect.

In short, the end() method is a very practical method, which can easily return to the previous state in chain operations. Being proficient in this method can improve the efficiency of your code and make it easier to maintain.

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