This time I will show you how to implement the calculator function with JavaScript. What are the precautions for implementing the calculator function with JavaScript? The following is a practical case. Let’s take a look. one time.
This computer mainly stores it in an array through a two-dimensional array, and then uses functions to control the displayed effect. Some keys occupy two columns. The colspan function is used to merge the two columns. First, the outside of the entire computer is After the style is designed, the main implementation code and renderings are as follows:
var btns=[ [ {text:"AC",id:"btn_C",value:"c",col:1}, {text:"Del",id:"btn_JJ",value:"✘",col:1}, {text:"%",id:"btn_BF",value:"%",col:1}, {text:"÷",id:"btn_CY",value:"/",col:1,cls:"yellow"}, ], [ {text:"7",id:"btn_C",value:"7",col:1}, {text:"8",id:"btn_JJ",value:"8",col:1}, {text:"9",id:"btn_BF",value:"9",col:1}, {text:"×",id:"btn_CY",value:"*",col:1,cls:"yellow"}, ], [ {text:"4",id:"btn_C",value:"4",col:1}, {text:"5",id:"btn_JJ",value:"5",col:1}, {text:"6",id:"btn_BF",value:"6",col:1}, {text:"-",id:"btn_CY",value:"-",col:1,cls:"yellow"}, ], [ {text:"1",id:"btn_C",value:"1",col:1}, {text:"2",id:"btn_JJ",value:"2",col:1}, {text:"3",id:"btn_BF",value:"3",col:1}, {text:"+",id:"btn_CY",value:"+",col:1,cls:"yellow"}, ], [ {text:"0",id:"btn_C",value:"0",col:2}, {text:".",id:"btn_JJ",value:".",col:1}, {text:"=",id:"btn_BF",value:"=",col:1,cls:"gray"}, ], ]; function creatUI(config){ var html=[]; for(var i=0,len=config.length;i<len;i++){ html.push("<tr>"); var arry=config[i]; for(var j=0;j<arry.length;j++) { var obj=arry[j]; html.push("<td colspan="+obj.col+" class='"+obj.cls+"' v='"+obj.value+"'>"+obj.text+"</td>"); } html.push("</tr>"); } var b = document.getElementById("tbody"); b.innerHTML=html.join(""); } creatUI(btns);
The main code for the entire calculator implementation is to add Click the event and save it in an array. Create some functions to determine whether the currently input value meets the calculation requirements. If so, pass the array value to the eval() function, calculate the result through this function, and pass the result to the display. The corresponding p is displayed to the user through innerText. As long as the implementation code is as follows:
function register(){ var container=document.getElementById("content"); var tds=document.getElementsByTagName("td"); var show=document.getElementById("show"); for(var i=0,len=tds.length;i<len;i++) { var block=tds[i]; block.onclick=function(){ var v=this.getAttribute("v"); //实现清零功能 if(v=="c"){ ac(); show.innerText="0"; return ; } inputs.push(v); //实现删除功能 if(v=="✘"){ if(inputs.length==0||inputs.length==1) { inputs.length=0; show.innerText='0'; } else{ inputs.length=inputs.length-2; } } //检测是不是相邻两个是不是操作符 checkNeiber(); //调用回显的函数 echoEcho(show); //检测如果已经有两个运算符的话,直接进行计算 if(isStartCompute()){ var result=eval(inputs.join("")); inputs.length=0; inputs[0]=result; show.innerText=result; inputs[1]=temp; //show.innerText=result; } //如果输入等号,直接让其输出结果 if(v=='=') { if(inputs.length==1) { inputs.length=0; show.innerText=0; } else{ inputs.length=inputs.length-1; var result=eval(inputs.join("")); inputs.length=0; inputs[0]=result; show.innerText=result; inputs.length=0; } } } } }
The remaining functions are to determine whether the calculator can perform calculations. There are many pitfalls in the function. Please pay attention. I Show everyone the effect of using this calculator:
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title>简单的计算器</title> <style type="text/css"> *{ margin: 0px; padding: 0px; } .mytable{ border: 1px solid black; border-spacing: 0px; margin: 0 auto; } .mytable td{ border: 1px solid black; padding: 20px; text-align: center; vertical-align: middle; cursor:pointer !important; } td:hover{ background-color: lightsteelblue; } #content{ font-size: 20px; margin: 0 auto; width:262px; background-color:white; } .screen{ height: 80px; padding-right: 8px; background-color:rgb(112,131,147); opacity: 0.8; text-align: right; line-height:80px; font-size: 40px; overflow: hidden; } .yellow{ background-color:rgb(255,152,62); } .gray{ background-color: #808080; } </style> </head> <body> <p id="content"> <p class="screen" id="show">0</p> <p class="btns"> <table class="mytable"> <tbody id="tbody"> </tbody> </table> </p> </p> <script type="text/javascript"> var btns=[ [ {text:"AC",id:"btn_C",value:"c",col:1}, {text:"Del",id:"btn_JJ",value:"✘",col:1}, {text:"%",id:"btn_BF",value:"%",col:1}, {text:"÷",id:"btn_CY",value:"/",col:1,cls:"yellow"}, ], [ {text:"7",id:"btn_C",value:"7",col:1}, {text:"8",id:"btn_JJ",value:"8",col:1}, {text:"9",id:"btn_BF",value:"9",col:1}, {text:"×",id:"btn_CY",value:"*",col:1,cls:"yellow"}, ], [ {text:"4",id:"btn_C",value:"4",col:1}, {text:"5",id:"btn_JJ",value:"5",col:1}, {text:"6",id:"btn_BF",value:"6",col:1}, {text:"-",id:"btn_CY",value:"-",col:1,cls:"yellow"}, ], [ {text:"1",id:"btn_C",value:"1",col:1}, {text:"2",id:"btn_JJ",value:"2",col:1}, {text:"3",id:"btn_BF",value:"3",col:1}, {text:"+",id:"btn_CY",value:"+",col:1,cls:"yellow"}, ], [ {text:"0",id:"btn_C",value:"0",col:2}, {text:".",id:"btn_JJ",value:".",col:1}, {text:"=",id:"btn_BF",value:"=",col:1,cls:"gray"}, ], ]; function creatUI(config){ var html=[]; for(var i=0,len=config.length;i<len;i++){ html.push("<tr>"); var arry=config[i]; for(var j=0;j<arry.length;j++) { var obj=arry[j]; html.push("<td colspan="+obj.col+" class='"+obj.cls+"' v='"+obj.value+"'>"+obj.text+"</td>"); } html.push("</tr>"); } var b = document.getElementById("tbody"); b.innerHTML=html.join(""); } creatUI(btns); //注册点击事件 var inputs=[];//定义用户输入按钮的数组 function register(){ var container=document.getElementById("content"); var tds=document.getElementsByTagName("td"); var show=document.getElementById("show"); for(var i=0,len=tds.length;i<len;i++) { var block=tds[i]; block.onclick=function(){ var v=this.getAttribute("v"); //实现清零功能 if(v=="c"){ ac(); show.innerText="0"; return ; } inputs.push(v); //实现删除功能 if(v=="✘"){ if(inputs.length==0||inputs.length==1) { inputs.length=0; show.innerText='0'; } else{ inputs.length=inputs.length-2; } } //检测是不是相邻两个是不是操作符 checkNeiber(); //调用回显的函数 echoEcho(show); //检测如果已经有两个运算符的话,直接进行计算 if(isStartCompute()){ var result=eval(inputs.join("")); inputs.length=0; inputs[0]=result; show.innerText=result; inputs[1]=temp; //show.innerText=result; } //如果输入等号,直接让其输出结果 if(v=='=') { if(inputs.length==1) { inputs.length=0; show.innerText=0; } else{ inputs.length=inputs.length-1; var result=eval(inputs.join("")); inputs.length=0; inputs[0]=result; show.innerText=result; inputs.length=0; } } } } } //检测到两个操作符的时候,就进行计算 function isStartCompute(){ var ctn=0; for(var i=0;i<inputs.length;i++){ var ip=inputs[i]; if(ip=="+"||ip=="-"||ip=="*"||ip=="/"||ip=="%") { ctn++; } if(ctn>=2) { temp=inputs[i]; inputs.length=inputs.length-1; return true; } if(ip=="=" && checkNumber(inputs[i+1])){ var num=inputs[i+1]; inputs.length=0; inputs[0]=num; return true; } } } //判断如果是两个相邻的操作符的情况 function checkNeiber(){ for(var i=0;i<inputs.length;i++) { if((inputs[i]=="+"||inputs[i]=="-"||inputs[i]=="*"||inputs[i]=="/"||inputs[i]=="%"||inputs[i]=="=")&&(inputs[i+1]=="+"||inputs[i+1]=="-"||inputs[i+1]=="*"||inputs[i+1]=="/"||inputs[i+1]=="%"||inputs[i+1]=="=")) { var lastKey=inputs[i+1]; inputs.length=inputs.length-2; inputs.push(lastKey); return ; } } } function checkNumber(word){ word=parseInt(word); if(word>0 && word<9){ return true; } } //清零功能 function ac(){ inputs.length=0; echoEcho(); } //增加回显功能 function echoEcho(showl){ if(!showl){ showl=document.getElementById("show"); } if(inputs.length==0){ showl.innerText="0"; } showl.innerText =inputs.join(""); } window.onload = function(){ register(); } </script> </body></html>I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website! Recommended reading:
Detailed explanation of command pattern of JS design pattern
What are the differences between call, apply and bind in javascript
The above is the detailed content of How to implement calculator function in javascript. For more information, please follow other related articles on the PHP Chinese website!

The differences in performance and efficiency between Python and JavaScript are mainly reflected in: 1) As an interpreted language, Python runs slowly but has high development efficiency and is suitable for rapid prototype development; 2) JavaScript is limited to single thread in the browser, but multi-threading and asynchronous I/O can be used to improve performance in Node.js, and both have advantages in actual projects.

JavaScript originated in 1995 and was created by Brandon Ike, and realized the language into C. 1.C language provides high performance and system-level programming capabilities for JavaScript. 2. JavaScript's memory management and performance optimization rely on C language. 3. The cross-platform feature of C language helps JavaScript run efficiently on different operating systems.

JavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Atom editor mac version download
The most popular open source editor

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

Zend Studio 13.0.1
Powerful PHP integrated development environment

SublimeText3 English version
Recommended: Win version, supports code prompts!

Notepad++7.3.1
Easy-to-use and free code editor
