How to use input in js

How to use JavaScript to operate input elements: Get DOM nodes, access attributes and values ​​(such as .value), add event listeners (such as focus, blur, input) Notes: The type of input elements affects the value processing method. Add events After the listener is installed, it should be removed when not in use. Use HTML5 validation attributes combined with JavaScript for value validation

How to use the input element in JavaScript

Introduction
The input element is an element in an HTML form used to receive user input. JavaScript can operate the input element through the DOM API to get and set its properties and values.

Usage steps
To use JavaScript to operate input elements, you need to follow the following steps:

1. Get input elements
Use document.getElementById() or document.querySelector() Get the DOM node of the input element.

2. Access attributes and values
Use the .value attribute to read or set the value of the input element.
Use the .placeholder property to read or set the placeholder text.
Use the .type attribute to get the type of the input element.

3. Add event listener
Use the addEventListener() method to add an event listener to the input element, such as:

• focus Event: Triggered when the input element gains focus.
• blur Event: Triggered when the input element loses focus.
• input Event: Triggered when the value in the input element changes.

Example
The following example demonstrates how to use JavaScript to get the value of an input element and display it in the console:

<code class="js">const input = document.getElementById("myInput");
console.log(input.value);</code>

Other methods
In addition to the above properties and methods, JavaScript can also use other methods to operate input elements:

• .focus(): Set focus to the input element.
• .blur(): Remove the focus of the input element.
• .select(): Select all text in the input element.
• .setCustomValidity(): Set the custom validation message of the input element.

Notes
When using JavaScript to operate input elements, you need to pay attention to the following points:

• The type of input element will affect its value processing method.
• After adding an event listener using the addEventListener() method, remember to remove it when not in use.
• When validating the value of the input element, it should be combined with HTML5 input validation attributes, such as required and pattern.

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