根据现有HTML框架，写出加减乘除取模的五个函数
注意点：除数不能为0
取值需要强制转换为浮点数
<!DOCTYPEhtml><htmllang="en"><head><metacharset="UTF-8"><title>简单计算器</title></head><body><div><inputtype="text"size="5"id="num1"value=""/><selectid="ysf"><optionvalue="+">+</option><optionvalue="-">-</option><optionvalue="*">*</option><optionvalue="/">/</option><optionvalue="%">%</option></select><inputtype="text"size="5"id="num2"value=""/><inputtype="button"value="计算"id="btn"/></div><pid="res"></p><script>/**FIsNaN*判断是否为数字类型*true:数值类型*false:非数值类型**/functionFIsNaN(value){return(typeofvalue==='number'&&!isNaN(value));}functionadd(a,b){returna+b;}functionsub(a,b){returna-b;}functionmultiply(a,b){returna*b;}functiondiv(a,b){returna/b;}functionmod(a,b){returna%b;}//获取按钮注册事件document.getElementById('btn').onclick=function(){varnum1=parseFloat(document.getElementById('num1').value);varnum2=parseFloat(document.getElementById('num2').value);varysf=document.getElementById('ysf').value;console.log(typeofnum1);/*console.log(num1+ysf+num2);*/console.log(typeofysf);/*document.getElementById('res').innerHTML=num1+"---"+num2+"---"+ysf;*/varres=document.getElementById('res');if(ysf==='+'){if(FIsNaN(num1)&&FIsNaN(num2)){res.innerHTML=num1+'+'+num2+'='+add(num1,num2);}else{res.innerHTML='请输入正确的数字';}}elseif(ysf==='-'){if(FIsNaN(num1)&&FIsNaN(num2)){res.innerHTML=num1+'-'+num2+'='+sub(num1,num2);}else{res.innerHTML='请输入正确的数字';}}elseif(ysf==='*'){if(FIsNaN(num1)&&FIsNaN(num2)){res.innerHTML=num1+'*'+num2+'='+multiply(num1,num2);}else{res.innerHTML='请输入正确的数字';}}elseif(ysf==='/'){//除数不能为0if(FIsNaN(num1)&&FIsNaN(num2)){if(num2===0){res.innerHTML='除数不能为零';return;}else{res.innerHTML=num1+'/'+num2+'='+div(num1,num2);}}else{res.innerHTML='请输入正确的数字';}}elseif(ysf==='%'){//除数不能为0if(FIsNaN(num1)&&FIsNaN(num2)){if(num2===0){res.innerHTML='除数不能为零';return;}else{res.innerHTML=num1+'%'+num2+'='+mod(num1,num2);}}else{res.innerHTML='请输入正确的数字';}}else{res.innerHTML='请输入正确的数字';}};</script></body></html>
-利用表格table,tr,td来格式化显示-如果想要美观一些，在每一个单元格输出内容后加上空格-利用取模来实现行间颜色的变换-利用双重循环的的条件来限定制表语句的层次感。
<!DOCTYPEhtml><htmllang="en"><head><metacharset="UTF-8"><title>Title</title></head><body><script>/**打印99乘法口诀表**/document.write('<h1>九九乘法口诀表</h1>')for(vari=1;i<10;i++){for(varj=1;j<=i;j++){document.write(i+'x'+j+'='+i*j+' ');}document.write('<br/>');}/**打印倒三角99乘法口诀表**/document.write('<h1>倒序九九乘法口诀表</h1>')document.write('<tableborder="1">');for(vari=1;i<10;i++){if(i%2==0){document.write('<trbgcolor="red">');}else{document.write('<trbgcolor="#ccc">');}for(varj=9;j>=i;j--){document.write('<td>');document.write(i+'x'+j+'='+i*j+' ');document.write('</td>');}document.write('</tr>');}document.write('</table>');//累加函数，可变长度参数列表,argumentsfunctionnums(){console.log(arguments);vartotal=0;for(vari=0;i<arguments.length;i++){total+=arguments[i];}returntotal;}//nums(1,2,3,4,5,6,7,8)vara=nums(1,2,3,4,5,6,7,8);console.log(a);</script></body></html>
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