視頻網(wǎng)站logo怎么做的html底部友情鏈接代碼
文章目錄
- 一、JavaScript簡介
- 二、JavaScript引入方式
- 1、內(nèi)部腳本
- 2、外部腳本
- 三、JavaScript基礎語法
- 1、書寫語法&輸出語句
- 2、變量&數(shù)據(jù)類型
- 3、運算符
- 4、流程控制語句&函數(shù)
- 四、JavaScript對象
- 1、Array
- 2、String
- 3、自定義對象
- 五、BOM
- 1、Window
- 2、History
- 3、Location
- 六、DOM
- 1、獲取Element對象
- 2、常見HTML Element對象的使用
- 七、事件監(jiān)聽
- 1、事件綁定
- 2、常見事件
- 八、案例：表單驗證
- 九、正則表達式
一、JavaScript簡介
二、JavaScript引入方式
1、內(nèi)部腳本
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><script>alert("Helo js")
</script></body></html>
2、外部腳本
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><script src="../js/demo.js"></script></body></html>
alert("Hello js")
三、JavaScript基礎語法
1、書寫語法&輸出語句
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body><script>window.alert("Hello js1");//寫入警告框document.write("Hello js2");//寫入html頁面console.log("Hello js3");//寫入瀏覽器控制臺
</script></body></html>
2、變量&數(shù)據(jù)類型
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><script>// var test = 20;// test = "張三";// alert(test);/*var:1、作用域:全局變量2、變量可以重復定義*/{var age = 18;//var age = 20;}alert(age);const PI =3.14;
</script></body>
</html>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><script>//numbervar age = 20;var price = 99.8;alert(typeof age);alert(typeof price);//Stringvar ch = 'a';var name = '張三';var addr = "北京";alert(typeof ch);alert(typeof name);alert(typeof addr);//booleanvar flag1 = true;var flag2 = false;alert(typeof flag1);alert(typeof flag2);//nullvar obj = null;alert(typeof obj);//object//underfinedvar a;alert(typeof a);
</script></body>
</html>
3、運算符
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><script>/*==:1、判斷類型是否一樣，如果不一樣，則進行類型轉換2、再去比較值===:全等于1、判斷類型是否一樣，如果不一樣，直接返回false2、再去比較值*/var age1 = 18;var age2 = '18';//alert(age1 == age2);//truealert(age1 === age2);//false/*類型轉換：*其他類型轉換為number：1、String：按照字符串的字面值，轉換為數(shù)字.如果字面值不是數(shù)字，則轉為NaN。一般使用parseInt2、bollean：true 轉為1， false 轉為0*其他類型轉換為boolean：1、number:0和NaN轉化為false，其他數(shù)字轉換為true2、String:空字符串轉為false，其他字符串轉為true3、null:false4、undefined:false*/// var str = +'aaa';var str = +'20';alert(parseInt(str) + 1);var flag = +true;alert(flag);var flag = 0;var flag = 'asd';if(flag){alert("轉化為ture");}else {alert("轉換為false");}var str = 'asd';//健壯性判斷//if (str != null && str.length > 0)if(str){alert("轉化為ture");}else {alert("轉換為false");}
</script></body>
</html>
4、流程控制語句&函數(shù)
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><script>//1、ifvar count = 3;if (count == 3) {alert(count);}//2、switchvar num = 3;switch (num) {case 1: {alert("星期一");break;}case 2: {alert("星期二");break;}case 3: {alert("星期三");break;}case 4: {alert("星期四");break;}case 5: {alert("星期五");break;}case 6: {alert("星期六");break;}case 7: {alert("星期日");break;}default:{alert("信息有誤");break;}}//3、forvar sum = 0;for (let i = 1; i <= 100; i++){sum += 1;}alert(sum);//4、whilevar i = 1;while (i <= 100){sum += 1;i++;}alert(sum);
</script></body>
</html>
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>function add(a, b) {return a + b;}var result = add(1, 2);alert(result);var add = function (a, b) {return a + b;}var result = add(1, 2);alert(result);</script>
</body>
</html>
四、JavaScript對象
1、Array
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>//方式一var arr = new Array(1,2.3);alert(arr);//方式二var arr2 = [1,2,3];alert(arr2);//訪問arr[0] = 10;alert(arr);//特點:JavaScript數(shù)組相當于Java中集合，變長變類型//變長var arr3 = [1,2,3,];arr3[10] = 10;alert(arr3[10]);alert(arr3[9]);//變類型arr3[5] = "你好";alert(arr3[5]);alert(arr3)//屬性：length:數(shù)組中元素的個數(shù)var arr4 = [1,2,3];for (let i = 0; i < arr4.length; i++) {alert(arr4[i]);}//方法//push:添加方法var arr5 = [1,2,3];arr5.push(10);//splice:刪除元素arr5.splice(0,1);alert(arr5);
</script>
</body>
</html>
2、String
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>//方式一var str1 = new String("abc");//方式二var str2 = "abc";var str3 = 'abc';//lengthalert(str3.length);//trim():去除字符串前后兩端的空白字符var str4 = ' abc ';alert(1 + str4.trim() + 1);
</script>
</body>
</html>
3、自定義對象
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>var person = {name : "張三",age : 18,eat : function () {alert("吃飯")}};alert(person.age);alert(person.age);person.eat();
</script>
</body>
</html>
五、BOM
1、Window
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>//alertwindow.alert("abc");alert("bbb");//confirm,點擊確定按鈕，返回true，點擊取消按鈕，返回falsevar flag = confirm("刪除？");if (flag){//邏輯刪除}//定時器/*setTimeout:(function,毫秒值)：在一定時間間隔后執(zhí)行一個function，只執(zhí)行一次setInterval:(function,毫秒值)：在一定時間間隔后執(zhí)行一個function，循環(huán)執(zhí)行*/setTimeout(function (){alert("你好");},3000);setInterval(function (){alert("你好");},3000);
</script>
</body>
</html>
2、History
3、Location
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>alert("跳轉")location.href = "https://www.baidu.com";//3秒跳轉到首頁document.write("3秒");setTimeout(function () {location.href = "https://www.baidu.com";},3000);
</script>
</body>
</html>
六、DOM
1、獲取Element對象
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<img id="light" src="../img/off.gif"><br><div class="cls">傳智教育</div><br>
<div class="cls">黑馬程序員</div><br><input type="checkbox" name="hobby"> 電影
<input type="checkbox" name="hobby"> 旅游
<input type="checkbox" name="hobby"> 游戲
<br><script>//1、getElementById:根據(jù)id屬性值獲取，返回一個Element對象var img = document.getElementById("light");alert(img);//2、getElementsByTagName:根據(jù)標簽名稱獲取，返回Element對象數(shù)組var divs = document.getElementsByTagName("div");alert(divs.length);for (let i = 0; i < divs.length; i++) {alert(divs[i]);}//3、getElementsByName:根據(jù)name屬性值獲取，返回Element對象數(shù)組var hobbys = document.getElementsByName("hobby");for (let i = 0; i < hobbys.length; i++) {alert(hobbys[i]);}//4、getElementsByClassName:根據(jù)class屬性值獲取，返回Element對象數(shù)組var clss = document.getElementsByClassName("cls");for (let i = 0; i < clss.length; i++) {alert(clss[i]);}
</script></body>
</html>
2、常見HTML Element對象的使用
var divs = document.getElementsByTagName("div");/*style:設置元素css樣式innerHTML:設置元素內(nèi)容*/for (let i = 0; i < divs.length; i++) {divs[i].style.color = '紅色';divs[i].innerHTML = '你好';}
var hobbys = document.getElementsByName("hobby");for (let i = 0; i < hobbys.length; i++) {hobbys[i].checked = true;}
七、事件監(jiān)聽
1、事件綁定
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<input type="button" value="點我" onclick="on()"><br>
<input type="button" value="再點我" id="btn">
<script>function on(){alert("我被點了");}document.getElementById("btn").onclick = function (){alert("我被點了");}
</script>
</body>
</html>
2、常見事件
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<form id="register" action="#"><input type="text" name="username" /><input type="submit" value="提交">
</form><script>document.getElementById("register").onsubmit = function () {//onsubmit 返回true，則表單會被提交，返回false，則表單不會提交return true;}
</script>
</body>
</html>
八、案例：表單驗證
九、正則表達式
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script>//規(guī)則: 單詞字符：6~12var reg = /^\w{6,12}$/;var str = 'asd';var flag = reg.test(str);alert(flag);</script>
</body>
</html>