javascript/ex03.html at master · sangmin0816/javascript · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        button {width: 50px; height: 30px;}
    </style>
</head>
<body>
    <script>
        console.log(true/false);
    </script>
    <div id="display">Let's Calculate</div>
    <input type="number" size="5" min="1" max="500" id="num1" required="required">
    <br>
    <input type="number" size="5" min="1" max="500" id="num2" required="required">
    <hr>
    <button id="btn1" onclick="func(1)">+</button>
    <button id="btn2" onclick="func(2)">*</button>
    <button id="btn3" onclick="func(3)">-</button>
    <button id="btn4" onclick="func(4)">/</button>
    <script>
        function func(op){
            var num1 = document.getElementById("num1").value;
            var num2 = document.getElementById("num2").value;
            display = document.getElementById("display");
            if(num1==""||num2==""){
                alert("you should check your input");
            }
            else if(num2=="0"){
                alert("Can't divide with 0");
            }
            else{
                num1 = parseInt(num1);
                num2 = parseInt(num2);
                switch(op){
                    case 1:
                        display.innerText = num1+num2;
                        break;
                    case 2:
                        display.innerText = num1*num2;
                        break
                    case 3:
                        display.innerText = num1-num2;
                        break;
                    case 4:
                        display.innerText = num1/num2;
                        break;
                    case 5:
                        display.innerText = num%num2;
                }
            }
        }
    </script>
</body>
</html>