day 14 JS 練習
實例練習
1、搜索框
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <script> function Focus(){ var input=document.getElementById("ID1"); if (input.value=="請輸入用戶名"){ input.value=""; } } function Blurs(){搜索框var ele=document.getElementById("ID1"); var val=ele.value; if(!val.trim()){ ele.value="請輸入用戶名"; } } </script> </head> <body> <input id="ID1" type="text" value="請輸入用戶名" onblur="Blurs()" onfocus="Focus()"> </body> </html>
2、模態對話框
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> .back{ background模態對話框-color: white; height: 2000px; } .shade{ position: fixed; top: 0; bottom: 0; left:0; right: 0; background-color: grey; opacity: 0.4; } .hide{ display: none; } .models{ position: fixed; top:50%; left: 50%; margin-left: -100px; margin-top: -100px; height: 200px; width: 200px; background-color: wheat; } </style> </head> <body> <div class="back"> <input class="c" type="button" value="click"> </div> <div class="shade hide handles"></div> <div class="models hide handles"> <input class="c" type="button" value="cancel"> </div> <script> var eles=document.getElementsByClassName("c"); var handles=document.getElementsByClassName("handles"); for(var i=0;i<eles.length;i++){ eles[i].onclick=function(){ if(this.value=="click"){ for(var j=0;j<handles.length;j++){ handles[j].classList.remove("hide"); } } else { for(var j=0;j<handles.length;j++){ handles[j].classList.add("hide"); } } } } </script> </body> </html>
3、表格案例
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <button class="select_all">全選</button> <button class="select_reverse">反選</button> <button class="cancel">取消</button> <hr> <table class="server_table" border="2px" cellspacing="2px"> <tr> <td><input type="checkbox" class="item"></td> <td>111</td> <td>111</td> <td>111</td> </tr> <tr> <td><input type="checkbox" class="item"></td> <td>222</td> <td>222</td> <td>222</td> </tr> <tr> <td><input type="checkbox" class="item"></td> <td>333</td> <td>333</td> <td>333</td> </tr> <tr> <td><input type="checkbox" class="item"></td> <td>444</td> <td>444</td> <td>444</td> </tr> </table> <script> /* var ele_all=document.getElementsByClassName("select_all")[0]; var ele_reverse=document.getElementsByClassName("select_reverse")[0]; var ele_cancel=document.getElementsByClassName("cancel")[0]; var input_arr=document.getElementsByClassName("item"); ele_all.onclick=function(){ for(var i=0;i<input_arr.length;i++){ console.log(input_arr[i]); var input=input_arr[i]; input.checked=true; } }; ele_cancel.onclick=function(){ for(var i=0;i<input_arr.length;i++){ console.log(input_arr[i]); var input=input_arr[i]; input.checked=false; } }; ele_reverse.onclick=function(){ for(var i=0;i<input_arr.length;i++){ console.log(input_arr[i]); var input=input_arr[i]; if(input.checked){ input.checked=false; } else{ input.checked=true; } } }; */ var input_arr=document.getElementsByClassName("item"); var button_arr=document.getElementsByTagName("button"); for(var i=0;i<button_arr.length;i++){ button_arr[i].onclick=function(){ for (var j=0;j<input_arr.length;j++){ var inp=input_arr[j] if(this.innerText=="全選"){ console.log("ok"); inp.checked=true; } else if(this.innerText=="取消"){ inp.checked=false; } else { if(inp.checked){ inp.checked=false; }else { inp.checked=true; } } } } } </script> </body> </html>表格案例
4、select移動
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> .outer{ margin: 0 auto; background-color: darkgray; width: 80%; height: 600px;margin-top: 30px; word-spacing: -5px; } #left{ display: inline-block; width: 100px ; height: 140px; background-color: wheat; text-align: center; } #choice{ display: inline-block; height: 140px; background-color: darkolivegreen; vertical-align: top; padding:0 5px; } #choice button{ margin-top: 20px; } #right{ display: inline-block; width: 100px ; height: 140px; background-color: wheat; text-align: center; line-height: 140px; } </style> </head> <body> <div class="outer"> <select multiple="multiple" size="5" id="left"> <option>紅樓夢</option> <option>西遊記</option> <option>水滸傳</option> <option>JinPingMei</option> <option>三國演義</option> </select> <span id="choice"> <button id="choose_move"> > </button><br> <button id="all_move"> >> </button> </span> <select multiple="multiple" size="10" id="right"> <option>放風箏的人</option> </select> </div> <script> var choose_move=document.getElementById("choose_move"); var all_move=document.getElementById("all_move"); var right=document.getElementById("right"); var left=document.getElementById("left"); var options=left.options; choose_move.onclick=function(){ for (var i=0; i<options.length;i++){ var option=options[i]; if(option.selected==true){ // var news=option.cloneNode(true); // console.log(news); right.appendChild(option); i--; } } }; all_move.onclick=function(){ for (var i=0; i<options.length;i++){ var option=options[i]; right.appendChild(option); i--; }; }; /* var buttons=document.getElementsByTagName("button"); for(var i=0;i<buttons.length;i++) { buttons[i].onclick = function () { for (var i = 0; i < options.length; i++) { var option = options[i]; if (this.innerText == ">") { if (option.selected == true) { // var news=option.cloneNode(true); // console.log(news); right.appendChild(option); i--; } } else { right.appendChild(option); i--; } } }; } */ </script> </body> </html>select移動
5、二級聯動
<select id="province"> <option>請選擇省:</option> </select> <select id="city"> <option>請選擇市:</option> </select> <script> data={"河北省":["廊坊","邯鄲"],"北京":["朝陽區","海澱區"]}; var p=document.getElementById("province"); var c=document.getElementById("city"); for(var i in data){ var option_pro=document.createElement("option"); option_pro.innerHTML=i; p.appendChild(option_pro); } p.onchange=function(){ pro=(this.options[this.selectedIndex]).innerHTML; citys=data[pro]; c.options.length=0; for (var i in citys){ var option_city=document.createElement("option"); option_city.innerHTML=citys[i]; c.appendChild(option_city); } } </script>二級聯動
6、跑馬燈與tab切換
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>tab</title> <style> *{margin:0; padding:0; list-style:none;} body{ font-family: "Helvetica Neue", "Hiragino Sans GB", "Microsoft YaHei", "\9ED1\4F53", Arial, sans-serif; } h3{ text-align: center; color:darkcyan; margin-top: 30px; letter-spacing: 5px; } .box{ width: 1000px; margin:50px auto 0px; } #title{ line-height: 40px; background-color: rgb(247,247,247); font-size: 16px; font-weight: bold; color: rgb(102,102,102); } #title span{ float: left; width: 166px; text-align: center; } #title span:hover{ /*color: black;*/ cursor: pointer; } #content{ margin-top: 20px; } #content li{ width: 1050px; display: none; background-color: rgb(247,247,247); } #content li div{ width: 156px; margin-right: 14px; float: left; text-align: center; } #content li div a{ font-size: 14px; color: black; line-height: 14px; /* float: left;*/ display: inline-block; margin-top: 10px; } #content li a:hover{ color: #B70606; } #content li div span{ font-size: 16px; line-height: 16px; /*float: left;*/ display: block; color: rgb(102,102,102); margin-top: 10px; } #content img{ float: left; width: 155px; height: 250px; } #title .select{ background-color: #2459a2; color: white; border-radius: 10%; } #content .show{ display: block; } .show span{ color: red!important; font-size: 30px; } </style> </head> <body> <h3 id="wel">京東商城歡迎您</h3> <!-- direction="right up down left" --> <!-- behavior:滾動方式(包括3個值:scroll、slide、alternate) --> <!-- 說明:scroll:循環滾動,默認效果;slide:只滾動一次就停止;alternate:來回交替進行滾動。 --> <!-- scrollamount="5" 滾動速度 --> <marquee behavior="scroll" direction="right">歡迎您苑昊先生</marquee> <script> function test(){ var mywel = document.getElementById("wel"); var content = mywel.innerText; var f_content = content.charAt(0); var l_content = content.substring(1,content.length); var new_content = l_content + f_content; mywel.innerText = new_content; } // setInterval("test();", 500); </script> <div class="box"> <p id="title"> <span class="select">家用電器</span> <span>家具</span> <span>汽車</span> <span>食品</span> <span>女鞋</span> <span>醫療保健</span> </p> <ul id="content"> <li class="show"> <div><img src="https://img10.360buyimg.com/n1/s450x450_jfs/t4786/325/2470647304/119102/9e1a4ed5/59005841Nd786a8df.jpg" alt="冰箱"><a href="#">容聲(Ronshen)冰箱</a><span>價格:5600</span></div> <div><img src="https://img12.360buyimg.com/n1/s450x450_jfs/t3037/347/1290968859/201366/7c1028a0/57c00194N9d0a54c6.jpg" alt="洗衣機"><a href="#">海爾洗衣機</a><span>價格:5400</span></div> <div><img src="https://img11.360buyimg.com/n1/jfs/t3289/128/2393835119/236360/af1d283b/57e0f300N53dde603.jpg" alt="電飯煲"><a href="#">福庫(CUCKOO)電飯煲</a><span>價格:3999</span></div> <div><img src="https://img13.360buyimg.com/n1/jfs/t3235/137/2361713777/152258/a6908440/57e098c2N44a90a5d.jpg" alt="智能電視"><a href="#">三星智能電視</a><span>價格:8999</span></div> <div><img src="https://img10.360buyimg.com/n1/jfs/t2053/101/1391591157/215066/572e131b/5696ee9bN2376492d.jpg" alt="凈水器"><a href="#">凈水器</a><span>價格:1300</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3175/78/2357430273/262835/9a8e7f65/57e0a3e9Nbda39dd2.jpg" alt="空氣凈化器"><a href="#">空氣凈化器</a><span>價格:5300</span></div> </li> <li> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t1948/172/2877517581/556924/682eb107/56f63dc8Naddf77e5.jpg" alt="沙發"><a href="#">沙發</a><span>價格:2900</span></div> </li> <li> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> <div><img src="http://img11.360buyimg.com/n1/jfs/t4969/76/45396935/144539/347153d4/58d9cff4N36872ad6.jpg" alt="長安汽車"><a href="#">長安汽車</a><span>價格:12900</span></div> </li> <li> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t4414/110/2582917360/207971/b7e129ad/58f0ee1fN94425de1.jpg" alt="嘉興粽子"><a href="#">嘉興粽子</a><span>價格:1</span></div> </li> <li> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> <div><img src="https://img14.360buyimg.com/n1/jfs/t3079/298/5759209435/92674/14818594/587f1c33N53e5d2a9.jpg" alt="星期六"><a href="#">星期六</a><span>價格:439</span></div> </li> <li> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> <div><img src="https://img12.360buyimg.com/n1/jfs/t5755/127/1139389729/356866/99d4e869/5923e410Nb2983f70.jpg" alt="匯仁 腎寶片"><a href="#">匯仁 腎寶片</a><span>價格:322</span></div> </li> </ul> </div> <script> var title=document.getElementById(‘title‘); var content=document.getElementById(‘content‘); var category=title.getElementsByTagName(‘span‘); var item=content.getElementsByTagName(‘li‘); for (var i = 0; i < category.length; i++) { category[i].index=i; category[i].onclick=function(){ for (var j = 0; j < category.length; j++) { category[j].className=‘‘; item[j].className=‘‘; } this.className=‘select‘; item[this.index].className=‘show‘; } } </script> </body> </html>跑馬燈與tab切換
js擴展
js的作用域
作用域是JavaScript最重要的概念之一,想要學好JavaScript就需要理解JavaScript作用域和作用域鏈的工作原理。
任何程序設計語言都有作用域的概念,簡單的說,作用域就是變量與函數的可訪問範圍,即作用域控制著變量與函數的可見性和生命周期。在JavaScript中,變量的作用域有全局作用域和局部作用域兩種。
作用域
1. 全局作用域(Global Scope)
在代碼中任何地方都能訪問到的對象擁有全局作用域,一般來說一下幾種情形擁有全局作用域:
(1)最外層函數和在最外層函數外面定義的變量擁有全局作用域
var name="yuan"; function foo(){ var age=23; function inner(){ console.log(age); } inner(); } console.log(name); // yuan //console.log(age); // Uncaught ReferenceError: age is not defined foo(); // 23 inner(); // Uncaught ReferenceError: inner is not defined
(2)所有末定義直接賦值的變量自動聲明為擁有全局作用域,例如:
var name="yuan"; function foo(){ age=23; var sex="male" } foo(); console.log(age); // 23 console.log(sex); // sex is not defined
變量blog擁有全局作用域,而sex在函數外部無法訪問到。
(3)所有window對象的屬性擁有全局作用域
一般情況下,window對象的內置屬性都都擁有全局作用域,例如window.alert()、window.location、window.top等等。
2. 局部作用域(Local Scope)
和全局作用域相反,局部作用域一般只在固定的代碼片段內可訪問到,最常見的例如函數內部,所有在一些地方也會看到有人把這種作用域成為函數作用域.
如示例1中的age與inner都只有局部作用域。(js中if、for沒有自己的作用域)
作用域鏈(Scope Chain)
在JavaScript中,函數也是對象,實際上,JavaScript裏一切都是對象。函數對象和其它對象一樣,擁有可以通過代碼訪問的屬性和一系列僅供JavaScript引擎訪問的內部屬性。其中一個內部屬性是[[Scope]],由ECMA-262標準第三版定義,該內部屬性包含了函數被創建的作用域中對象的集合,這個集合被稱為函數的作用域鏈,它決定了哪些數據能被函數訪問。
示例演示
please have a try:
//-----**********************例1********************************* var s=12; function f(){ console.log(s); var s=12; // if s=12 console.log(s) } f(); //-----**********************例2********************************* var s=10; function foo(){ console.log(s); var s=5; console.log(s); function s(){console.log("ok")}// 函數的定於或聲明是在詞法分析時完成的,執行時已不再有任何操作 console.log(s); } foo(); //-----***********************例3******************************** function bar(age) { console.log(age); var age = 99; var sex= ‘male‘; console.log(age); function age() { alert(123) }; console.log(age); return 100; } result=bar(5); //-----********************************************************
結果分析
我相信大家一定會有想不到的結果,接下來我們就以最復雜的例3來分析整個過程。
當一個函數創建後,它的作用域鏈會被創建此函數的作用域中可訪問的數據對象填充。在函數bar創建時,它的作用域鏈中會填入一個全局對象,該全局對象包含了所有全局變量,如下圖所示:
解析到函數調用時,即bar(5),會生成一個active object的對象,該對象包含了函數的所有局部變量、命名參數、參數集合以及this,然後此對象會被推入作用域鏈的前端,當運行期上下文被銷毀,活動對象也隨之銷毀。新的作用域鏈如下圖所示:
過程解析:
function bar(age) { console.log(age); var age = 99; var sex="male"; console.log(age); function age(){ alert(123); } ; console.log(age); return 100; } result=bar(5); 一 詞法分析過程(涉及參數,局部變量聲明,函數聲明表達式): 1-1 、分析參數,有一個參數,形成一個 AO.age=undefine; 1-2 、接收參數 AO.age=5; 1-3 、分析變量聲明,有一個 var age, 發現 AO 上面有一個 AO.age ,則不做任何處理 1-4 、分析變量聲明,有一個 var sex,形成一個 AO.sex=undefine; 1-5 、分析函數聲明,有一個 function age(){} 聲明, 則把原有的 age 覆蓋成 AO.age=function(){}; 二 執行過程: 2-1 、執行第一個 console.log(age) 時,當前的 AO.age 是一個函數,所以輸出的一個函數 2-2 、這句 var age=99; 是對不 AO.age 的屬性賦值, AO.age=99 ,所以在第二個輸出的age是 99; 2-3 、同理第三個輸出的是 99, 因為中間沒有改變 age 值的語句了。 註意:執行階段: function age(){ alert(123) } ; 不進行任何操作,將執行語句復制給age這部操作是在詞法分析時,即運行前完成的。
day 14 JS 練習