JQuery val()用法及代碼示例

val()方法是jQuery中的內置方法，用於返回或設置所選元素的attribute值。此方法適用於HTML表單元素。

用法:下麵提供了三種使用此方法的方法：

```
$(selector).val()
```
參數：此方法不接受任何參數。
```
$(selector).val(value)
```
參數：此方法接受強製的單個參數值。用於指定屬性的值。
```
$(selector).val(function(index,current_value))
```
參數：該方法接受可選的單參數函數。它包含元素的索引位置和所選元素的當前值屬性。

返回值：此方法返回通過val()方法進行指定更改的所選元素。

以下示例說明了jQuery中的val()方法：

示例1:

<!DOCTYPE html> 
<html> 
    <head> 
        <title>The val Method</title> 
        <script src= 
        "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"> 
        </script> 
          
        <!-- jQuery code to show the working of this method -->
        <script> 
            $(document).ready(function() { 
                $("button").click(function() { 
                    $("input:text").val("GeeksforGeeks!"); 
                    $("input:text").css("color", "green"); 
                    $("input:text").css("font-size", "40px"); 
                    $("input:text").css("font-weight", "bold"); 
                    $("input:text").css("font-family", "times new roman"); 
                }); 
            }); 
        </script> 
        <style> 
            div { 
                background-color: lightgreen; 
                padding: 20px; 
                width: 41%; 
                min-height: 150px; 
                border: 2px solid green; 
            } 
               
            input { 
                border: 2px solid green; 
                padding-left: 15px; 
                width: 350px; 
                height: 80px; 
            } 
        </style> 
    </head> 
    <body> 
        <div> 
            <p> 
                <input type="text" name="user"> 
            </p> 
            <!-- click on this paragraph and see the change -->
            <button>Click Here!</button> 
        </div> 
    </body> 
</html>

輸出：
val method

示例2:此方法采用兩個值，第一個用於索引位置，第二個用於屬性值。無需傳遞索引位置，該函數將自動設置為null(n = 0)，並且“c”指定輸入字段的當前值。

<!DOCTYPE html> 
<html> 
    <head> 
        <title>The val Method</title> 
        <script src= 
        "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"> 
        </script> 
          
        <!-- jQuery code to show the working of this method -->
        <script> 
            $(document).ready(function() { 
                $("button").click(function() { 
                    $("input:text").val(function(n, c) { 
                        return c + " GeeksforGeeks!"; 
                    }); 
                }); 
            }); 
        </script> 
        <style> 
            div { 
                background-color: lightgreen; 
                padding: 20px; 
                width: 300px; 
                height: 80px; 
                border: 2px solid green; 
            } 
               
            input { 
                border: 2px solid green; 
                padding-left: 15px; 
                width: 220px; 
                font-weight: bold; 
                height: 30px; 
            } 
        </style> 
    </head> 
       
    <body> 
        <div> 
            <p> 
                <input type="text" name="user" value="Welcome To"> 
            </p> 
            <!-- click on this paragraph and see the change -->
            <button>Click Here!</button> 
        </div> 
    </body> 
</html>

輸出：
在單擊按鈕之前：

單擊按鈕後：

相關用法

注：本文由純淨天空篩選整理自kundankumarjha大神的英文原創作品 jQuery | val() with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。