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標籤：false var 筆記 isp ida off oob src image
<!DOCTYPE html><html><head><meta charset="utf-8"><title>菜鳥教程(runoob.com)</title><script>function displayDate(){ document.getElementById("demo").innerHTML=Date(); //先擷取id是demo的對象，在重新給對象裡面的內容賦值}</script></head><body><h1>我的第一個 JavaScript 程式</h1><p id="demo">這是一個段落</p><button type="button" onclick="displayDate()">顯示日期</button></body></html>
<!DOCTYPE html><html><head> <meta charset="utf-8"> <title>菜鳥教程(runoob.com)</title> </head><body> <script>function changeImage(){ element=document.getElementById(‘myimage‘) if (element.src.match("bulbon")) //預設的src是 src="/images/pic_bulboff",點擊的時候match()判斷src中是否包含字串bulbon { element.src="/images/pic_bulboff.gif"; } else { element.src="/images/pic_bulbon.gif"; }}</script><img id="myimage" onclick="changeImage()"src="/images/pic_bulboff.gif" width="100" height="180"><p>點擊燈泡就可以開啟或關閉這盞燈</p> </body></html>
x=document.getElementById("demo") //找到元素 x.style.color="#ff0000"; //改變樣式
function myFunction(){ var x=document.getElementById("demo").value; //擷取id的demo對象裡面你的值 if(x==""||isNaN(x)) { alert("不是數字"); }}
注意 var x=document.getElementById("demo").value; 如果有框框，比如input標籤用的是value
var x=document.getElementById("demo").innerHTML 沒有框框的，比如<p>標籤
var person={firstname:"John", lastname:"Doe", id:5566}; //建立對象
person.lastName; //兩種方式訪問對象屬性person["lastName"];
<!DOCTYPE html><html><head><meta charset="utf-8"><script>function validateForm() { var x = document.forms["myForm"]["fname"].value; //判斷表單中的fname的值是否存在 if (x == null || x == "") { alert("需要輸入名字。"); return false; }}</script></head><body><form name="myForm" action="demo_form.php"onsubmit="return validateForm()" method="post">名字: <input type="text" name="fname"><input type="submit" value="提交"></form></body></html>
<!DOCTYPE html><html><head><meta charset="utf-8"></head><body><form action="demo_form.php" method="post"> //自動驗證表單是否為空白 低版本瀏覽器不支援 <input type="text" name="fname" required="required"> <input type="submit" value="提交"></form><p>點擊提交按鈕，如果輸入框是空的，瀏覽器會提示錯誤資訊。</p></body></html>
javascript學習筆記
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