九九乘法表

打印九九乘法表

• 首先理解输出9*9的方阵

    <script>
        for (let q = 1; q <= 9; q++) {
            for (let i = 1; i <= 9; i++) {
                document.write('# &nbsp;');
            }
            document.write('<br>')
        }
    </script>

• 然后理解输出直角三角形

    <script>
        for (let i = 1; i <= 9; i++) {
            for (let j = 1; j <= i; j++) {	//important!!重点在于理解j<=i
                document.write(' # ');
            }
            document.write('<br>');
        }
    </script>

• 最后将＃替换成算式即可

    <script>
        for (let i = 1; i <= 9; i++) {
            for (let q = 1; q <= i; q++) {
                document.write(q + ' * ' + i + ' = ' + (i * q) + "&emsp;");
            }
            document.write('<br>')
        }
    </script>