


A simple jQuery calculator implements continuous calculation function_jquery
A simple jQuery calculator that just implements a continuous calculation function
<!DOCTYPE html> <html> <head> <meta charset="utf8"/> <title>Javascript计算器</title> </head> <body> <table> <tr> <td colspan="4"><input id="show" value="0"/></td> </tr> <tr> <td><button onclick="number(this)" value="7">7</button></td> <td><button onclick="number(this)" value="8">8</button></td> <td><button onclick="number(this)" value="9">9</button></td> <td><button onclick="calsym(this)" value="+">+</button></td> </tr> <tr> <td><button onclick="number(this)" value="4">4</button></td> <td><button onclick="number(this)" value="5">5</button></td> <td><button onclick="number(this)" value="6">6</button></td> <td><button onclick="calsym(this)" value="-">-</button></td> </tr> <tr> <td><button onclick="number(this)" value="1">1</button></td> <td><button onclick="number(this)" value="2">2</button></td> <td><button onclick="number(this)" value="3">3</button></td> <td><button onclick="calsym(this)" value="*">*</button></td> </tr> <tr> <td><button onclick="number(this)" value="0">0</button></td> <td><button onclick="calsym(this)" value="=">=</button></td> <td><button onclick="clearCal()" value="c">c</button></td> <td><button onclick="calsym(this)" value="/">/</button></td> </tr> </table> </body> <script type="text/javascript" src="jquery-1.9.1.js"></script> <script type="text/javascript" src="jquery-1.9.1.min.js"></script> <script type="text/javascript"> var num0 = null; var num1 = null; var symble = null; var lastclick = null; var symarr = new Array(); //符号集合 symarr[0] = '+'; symarr[1] = '/'; symarr[2] = '*'; symarr[3] = '-'; symarr[4] = '='; function number(n){ var numnow = $('#show'); var _exist=$.inArray(lastclick,symarr); //判断上次点击是否为符号 if (numnow.val() == 0 || _exist != -1) {//若显示框为0 或者上次点击为符号,则重新记录显示框 numnow.val($(n).val()); }else{ numnow.val(parseInt(numnow.val()) * 10 +parseInt($(n).val())); } lastclick = $(n).val(); // 更新上次点击 } function calsym(cs){ //符号点击事件响应 var numnow = $('#show'); var _exist=$.inArray(lastclick,symarr); if (num0 == null && symble == null) { //初始状态 num0 = numnow.val(); symble = $(cs).val(); }else if(num0 != null && num1 == null && _exist !=-1){ // 连续点操作符的处理,及第一次点击操作符处理 symble = $(cs).val(); }else{ //正常计算状态 num1 = numnow.val(); var result = calculate(symble,num0,num1); symble = $(cs).val(); //上行及本行:先计算之前的运算符及结果,再更新运算符为本次点击 num0 = result; numnow.val(result); num1 = null; } lastclick = $(cs).val(); // 更新上次点击 } function clearCal(){ //清空函数 $('#show').val('0'); num0 = null; num1 = null; symble = null; lastclick = null; } function calculate(sym,m,n){ //计算并返回结果 var res = null; m = parseInt(m); n = parseInt(n); switch(sym){ case '+': res = m+n; break; case '-': res = m-n; break; case '*': res = m*n; break; case '/': if (n == 0) { alert("false"); break; } res = m/n; break; default: break; } return res; } </script> </html>

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JavaScriptusestwotypesofcomments:single-line(//)andmulti-line(//).1)Use//forquicknotesorsingle-lineexplanations.2)Use//forlongerexplanationsorcommentingoutblocksofcode.Commentsshouldexplainthe'why',notthe'what',andbeplacedabovetherelevantcodeforclari

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Whether to choose Python or JavaScript depends on the project type: 1) Choose Python for data science and automation tasks; 2) Choose JavaScript for front-end and full-stack development. Python is favored for its powerful library in data processing and automation, while JavaScript is indispensable for its advantages in web interaction and full-stack development.

Python and JavaScript each have their own advantages, and the choice depends on project needs and personal preferences. 1. Python is easy to learn, with concise syntax, suitable for data science and back-end development, but has a slow execution speed. 2. JavaScript is everywhere in front-end development and has strong asynchronous programming capabilities. Node.js makes it suitable for full-stack development, but the syntax may be complex and error-prone.

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JavaScript can be used for front-end and back-end development. The front-end enhances the user experience through DOM operations, and the back-end handles server tasks through Node.js. 1. Front-end example: Change the content of the web page text. 2. Backend example: Create a Node.js server.

Choosing Python or JavaScript should be based on career development, learning curve and ecosystem: 1) Career development: Python is suitable for data science and back-end development, while JavaScript is suitable for front-end and full-stack development. 2) Learning curve: Python syntax is concise and suitable for beginners; JavaScript syntax is flexible. 3) Ecosystem: Python has rich scientific computing libraries, and JavaScript has a powerful front-end framework.


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