js05 随堂笔记 2/10

由*号组成正三角形

 for(var row=1;row<9;row++){
     for(var col=1;col<=row;col++){
         document.write("*");
     }
     document.write("
");
 }

输出：

**

---

---

---

---

---

...........

由*号组成倒三角形

 for(var col=9;col>=1;col--){
    for(var row<=col;row++){
        document.write("*");
     }
     document.write("
")
  }

输出：

---

---

---

.......

在控制台按口诀表排列，乘法口诀表

    for(var hang=1,s;hang<=9;hang++){
        for(var num=1;num<=hang;num++){
                    s+=hang+"*"+num+"="+(hang*num)+" ";
        }
          s=s+"\n";
    }
        console.log(s);

rest 用法

  function sum(...rest){
      var he=0;
      for(var i of rest){
          he+=i;
      }
      return he;
     }
  var  i,args =[];
      for (i=1;i<=100;i++){
        args.push(i);
      }
      if( sum()!==0 ){
          alert("测试失败：sum()="+sum());
      }else if (sum(1)!==1){
         alert("测试失败：sum(1)="+sum(1));
      }else if (sum(2,3)!==5){
         alert(sum.apply(null,args)!==5050){
      }