JS 简单计算器、九九乘法表实例演示

JS 简单计算器

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>简单计算器</title>
</head>
<body>
    <div style="width: 200px;margin: auto; background-color:rgb(184, 249, 237);">
        <input type="text" size="5" id="num1" value="" />
        <select id="ysf">
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
            <option value="%">%</option>
        </select>
        <input type="text" size="5" id="num2" value=""/>
        <input type="button" value="计算" id="btn" />
    </div>
    <p id="res" style="width: 200px;margin: 10px auto; background-color:rgb(184, 249, 237);"></p>
<script>
//获取按钮注册事件
document.getElementById('btn').onclick=function(){
    var num1 = document.getElementById('num1').value;
    var num2 = document.getElementById('num2').value;
    var ysf = document.getElementById('ysf').value;
    // 简单判断输入的内容只能是数字
    if (num1 == NaN || num2 == NaN){
        window.alert('请输入数字进行计算');
    }else{
        // document.getElementById('res').innerHTML=num1+"---"+num2+"---"+ysf;
        var res = document.getElementById('res');
        if(ysf == '+'){
            res.innerHTML = num1 + ysf + num2 + '=' + (parseInt(num1) + parseInt(num2));
        };
        if(ysf == '-'){
            res.innerHTML = num1 + ysf + num2 + '=' + (num1 - num2);
        };
        if(ysf == '*'){
            res.innerHTML = num1 + ysf + num2 + '=' + (num1 * num2);
        };
        if(ysf == '/'){
            // 判断被除数不能为0
            if(num2 == 0){
                window.alert('被除数不能为0');
            }else{
                res.innerHTML = num1 + ysf + num2 + '=' + (num1 / num2);
            } 
        };
    } 
};
</script>      
</body>
</html>

九九乘法表

上图

js代码

<script>
    document.write('<table border="1" width="800" align="center">')
    for(var row = 9; row > 0; row--){
        document.write('<tr>')
        for(var col = 1; col <= row; col++){
            document.write('<td>' + col + '*' + row + '=' + col * row + '</td>')
            // console.log(col + '*' + row + '=' + col * row) 
        }
        document.write('</tr>')
    }
    document.write('</table>')
</script>

JS 简单计算器

九九乘法表

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