如何通過Javascript在JSP中設置文本字段的值

Question

當用戶在“生成”按鈕上選擇並在文本字段中設置值時，我需要生成一個隨機數。 如何在“ randomNum”文本字段中設置“輸出變量”。

HTML代碼：

<form action="submit.jsp" method= "post" name="privateKey">
            Random String: <input type="text" name="randomNum" onkeyleave="generate()">
            <input type="button" name="generate" value="Generate!" >

</form>

使用Javascript：

     function generate() {
           char[] chars = "abcdefghijklmnopqrstuvwxyz".toCharArray();
           StringBuilder sb = new StringBuilder();
           Random random = new Random();
           for (int i = 0; i < 20; i++) {
               char c = chars[random.nextInt(chars.length)];
               sb.append(c);
           }
           String output = sb.toString();
        }

Answer 1

嘗試這個

HTML：

<form action="submit.jsp" method= "post" name="privateKey">
            Random String: <input type="text" name="randomNum" id="demo" onkeyleave="generate()">
            <input type="button" name="generate" value="Generate!" >

</form>

JavaScript的：

function generate() {
           char[] chars = "abcdefghijklmnopqrstuvwxyz".toCharArray();
           StringBuilder sb = new StringBuilder();
           Random random = new Random();
           for (int i = 0; i < 20; i++) {
               char c = chars[random.nextInt(chars.length)];
               sb.append(c);
           }
            document.getElementById("demo").value = sb.toString();
        }

Answer 2

設置輸入文字的ID：

 <input id="randomtxt" type="text" name="randomNum" onkeyleave="generate()">

函數的最后一行應更改：

 document.getElementById("randomtxt").value= sb.toString();