How to end the current loop in jquery

jQuery is the most commonly used JavaScript library. It simplifies many tedious operations in JavaScript development and provides a rich API, making it easier for developers to operate DOM, operate properties, event processing and animation effects, etc. .

There are two commonly used loop structures in jQuery, one is $.each() and the other is $.map(). During the looping process of these two loop structures, sometimes it is necessary to end the loop early, that is, to jump out of the current loop, in order to execute the code more efficiently. So, how to end the current loop, this article will introduce how to implement this function.

1. End of $.each() loop

$.each() is a method for traversing jQuery objects. It is a general method and cannot directly access any object. If you want to access a certain An object needs to be accessed through context.

In the $.each() loop, you can use the return false; statement to end the loop. This statement ends the loop and skips the rest of the code. For example, the following code:

$.each([1, 2, 3, 4], function (index, value) {
  console.log(value);
  if (value === 3) {
    return false;
  }
});

The output result is:

1
2
3

When the return false; statement in $.each() is executed, the loop is terminated and the following code will be ignored, so Number 4 has no output.

2. End of $.map() loop

$.map() method is a conversion method. It extracts the return value from each element by executing the specified function and returns a new array. The $.map() loop can also use the return statement to end the loop.

When the return statement is used in a $.map() loop, it does not terminate the loop like $.each() does. It will only terminate the current loop and continue executing the following code until the end of the loop. For example, the following code:

$.map([1, 2, 3, 4], function (value, index) {
  console.log(value);
  if (value === 3) {
    return;
  }
});

The output result is:

1
2
3
4

When the return statement in $.map() is executed, it will skip the number 3 and continue the loop. That's the difference.

3. Summary

In JavaScript development, the optimization of loop structures has always been a very important topic. When a certain condition is executed, sometimes it is necessary to end the loop early to improve code efficiency. In jQuery, early ending of the loop can be achieved through the return statement of the $.each() and $.map() methods.

When using the $.each() method, you only need to use the return false; statement inside the loop. When using the $.map() method, you can use the return statement to skip the current loop and continue executing the following code until the end of the loop.

However, frequent use of jump statements will reduce the readability of the code and make the code complex and difficult to understand. Therefore, in actual development, we should use these statements with caution in order to better maintain the code.

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