How to determine whether the value is empty in jquery

Jquery method to determine if the value is empty: first use the input tag to create a text input box and create a button button; then obtain the input object and use [val()] to obtain the content of the input input box; finally use if Determine the content. If the content is undefiend or empty, the prompt is empty.

Jquery method to determine if the value is empty:

1. Create a new html file and name it test.html , used to explain how to determine whether a value is a null value in jquery.

2. In the test.html file, in the p tag, use the input tag to create a text input box. Next, we will use the jquery method to determine whether the input value is empty. value.

3. In the test.html file, set the id attribute of the input tag to mytxt, which is mainly used to obtain the input object through the id below.

4. In the test.html file, use the button tag to create a button with the button name "Judge Null Value" and bind the onclick event to the button button. When the button is clicked, the isempty() function is executed.

5. In the js tag, create the isempty() function. Within the function, use the $ symbol to obtain the input object through the id (mytxt), and use val() to obtain the input. Enter the content of the box and save the value in the res variable.

6. In the isempty() function, use if to determine the value of the previous step. If the value is undefiend or empty, it will prompt "The obtained value is empty." , otherwise, output the obtained value.

#7. Open the test.html file in the browser to check the effect.

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