Java Script n script n script q language
- Slides: 33
在網頁中加入 Java. Script 程式 n 使用 script 標籤加入程式碼 n <script> 的屬性 q language & type q src q defer n 用 Java. Script 運算式來設定元件的屬性值 n Java. Script URL
範例 以下三行都是加入 Java. Script 的程式碼 <script>……</script > <script language=“JAVASCRIPT”> ……</script > <script type=“text/javascript”> ……</script > 加入 Java. Script 1. 3 版的程式碼 <script language=“JAVASCRIPT 1. 3”> ……</script > 加入 JScript 的程式碼 <script language=“JScript”> ……</script > 加入 VBScript 的程式碼 <script language=“VBScript”> ……</script >
src= url_of_script_source src 屬性用來加入存在外部檔案中的程式碼。Java. Script 程式檔通常以. js 為副檔名。 範例 插入與網頁同目錄的 Java. Script 程式檔 myscript. js <script src=“myscript. js”>…</script> 插入的 www. pu. edu. tw 伺服器中的 Java. Script 程式檔 lib. js <script src=“http: //www. pu. edu. tw/lib. js”>…</script>
用 Java. Script 運算式來設定元件的屬性值 (僅適用於 Netscape 4. x) attribute=“&{Java. Script Expression}” 範例 <script> <!-var rule. Width=100; //--> </script> 等同於 <HR WIDTH=120> …… <hr width=“&{rule. Width+20}”>
瀏覽器物件階層 瀏覽器會依據網頁內容建立下圖所示的物件階層,供 Java. Script 程式碼 使用: navigator frames[] forms[] location window anchors[] history links[] document images[] screen applets[] embeds[] elements[] 包含以下表單 元件物件的陣 列: Button Checkbox File. Upload Hidden Password Radio Select Submit Texrarea options[]
window: navigator: document: location: the top-level object; has properties that apply to the entire window. Each “child window” in a frames document also has a window object. has properties for the name and version of Navigator being used, for the MIME types supported by the client, and for the plug-ins installed on the client. contains properties based on the content of the document, such as title, background color, links, and forms. has properties based on the current URL. history: contains properties representing URLs the client has previously requested. screen: contains properties about the display.
<body> document. forms[0]. elements[0] <form method="post"> <p>姓名:<input type="text"> </p> document. forms[0]. elements[1] <p>性別:<input type="radio" value=“male">男 <input type=“radio” value=“female”>女 </p> <p> document. forms[0]. elements[2] document. forms[0]. elements[3] <input type="submit" value="送出"> <input type="reset" value="重設"> </p> </form> </body> document. forms[0]. elements[4]
使用名稱來存取網頁物件 我們可以使用元件的名稱來存取其對應的網頁物件。 HTML 元件的名稱可以用 NAME 屬性來設定。譬如: document. img 1 <body> <img name=img 1. . . > document. form 1 <form name=form 1. . . > document. form 1. text 1 <input type=text name=text 1. . . > <input type=button name=button 1. . . >. . . </form> </body> document. form 1. button 1
插入網頁內容 document 物件提供底下兩個方法讓我們可以動態地插入網頁 內容: document. write(string) document. writeln(string) // 輸出 string 後再加一個跳行字元 範例 底下的程式產生顯示 Hello, world! 訊息的網頁 <body> <script> document. write(“<h 1>Hello, world!</h 1>”); </script> </body>
範例 底下的程式產生顯示今天日期的網頁 <body> <script> var now = new Date(); document. write(“<p>Today is: ”); document. write(now. to. Locale. Date. String()); document. write(“</p>”); </script> </body>
範例 <!-- 以下的程式碼產生九九乘法表 --> <table border=1 cellspcing=1 cellpadding=3 width=450> <caption>九九乘法表</caption> <script> document. write("<tr align=right>") document. write("<th width=40 align=center>*</th>") for (var i = 1; i < 10; i++) document. write("<th width=40>" + i + "</th>") document. writeln("</tr>") for (var i = 1; i < 10; i++) { document. write("<tr align=right>") document. write("<th width=40 align=center>" + i + "</th>") for (var j = 1; j < 10; j++) document. write("<td width=40>" + i*j + "</td>") document. writeln("</tr>") } </script> </table>
alert Displays an Alert dialog box with a message and an OK button. 語法: alert (message) 範例 alert("這是限制級網站,未成年的訪客請離開")
confirm Displays a Confirm dialog box with the specified message and OK and Cancel buttons. 語法: confirm (message) 範例 confirm("你滿 18 歲了嗎?")
範例 <html> <head> <meta http-equiv="Content-Type“ content="text/html; charset=big 5"> <title>禁忌話題</title> <script> function verify_visitor () { if (confirm("你滿 18 歲了嗎?")) location. href = "http: //sex. pu. edu. tw" else location. href = "http: //www. disneyland. com" } </script> </head> <body on. Load="verify_visitor()"> <!-- 空白網頁 --> </body> </html>
有時網頁延遲載入,當事件發生時,處理的程式碼所指涉的物 件尚未建立,而造成網頁錯誤。譬如: <script> function show_time () { var now = new Date(); document. form 1. elements. timebox. value = now. to. Locale. Time. String(); } </script> <a href=“javascript: show_time(); void 0; ”>更新時間</a> <script>for (k = 0; k < 10000; k++) {}</script> <form name=form 1> 目前時間:<input type=text name=timebox> </form> 按下此超連結 時,瀏覽器可 能還沒處理到 表單 form 1
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