一些前端题目

var User = {
  count: 1,
  getCount: function() {
    return this.count;
  }
};
 
console.log(User.getCount());  // what?
var func = User.getCount;
console.log(func());  // what?

  var foo = 1,bar = 2,j,test;
  test = function(j) {
      j = 5;
      var bar = 5;
      foo = 5;
  }
  test(10);
  console.log(foo); //
  console.log(bar); //
  console.log(j); //

};
 
console.log(User.getCount());  // what?
var func = User.getCount;
console.log(func());  // what?

setTimeout(function() {
  console.log(1)
}, 0);
new Promise(function executor(resolve) {
  console.log(2);
  for( var i=0 ; i<10000 ; i++ ) {
    i == 9999 && resolve();
  }
  console.log(3);
}).then(function() {
  console.log(4);
});
console.log(5);

function foo() {this.value = 42;}
foo.prototype = {method: function () {return true;}};
function bar() {
    var value = 1;
    return{method:function(){return value;}};
}
foo.prototype = new bar();
console.log(foo.prototype.constructor); //
console.log(foo.prototype instanceof  bar); //
var test = new foo();
console.log(test instanceof foo);//
console.log(test instanceof bar);//
console.log(test.method());//

方法1：
<ul class='nav'>
    <li><a href="#content1">列表1</a></li>
    <li><a href="#content2">列表2</a></li>
</ul>
<div id="content1">列表1内容:123456</div>
<div id="content2">列表2内容:abcdefgkijkl</div>
<style type="text/css">
	#content1,
	#content2{
	    display:none;
	}
 
	#content1:target,
	#content2:target{
	    display:block;
	}
	#content1:target ~ .nav li{
	    // 改变li元素的背景色和字体颜色
	    &:first-child{
	        background:#ff7300;
	        color:#fff;
	    }
	}
	#content2:target ~ .nav li{
	    // 改变li元素的背景色和字体颜色
	    &:last-child{
	        background:#ff7300;
	        color:#fff;
	    }
	}
</style>
方法2：
<div class="container">
    <input class="nav1" id="li1" type="radio" name="nav">
    <input class="nav2" id="li2" type="radio" name="nav">
    <ul class='nav'>
        <li class='active'><label for="li1">列表1</label></li>
        <li><label for="li2">列表2</label></li>
    </ul>
    <div class="content">
        <div class="content1">列表1内容:123456</div>
        <div class="content1">列表2内容:abcdefgkijkl</div>
    </div>
</div>
<style type="text/css">
	.container{
    position:relative;
    width:400px;
    margin: 50px auto;
}
input{
    display:none;
}
.nav{
    position:relative;
    overflow:hidden;
}
li{
    width:200px;
    float:left;
    text-align:center;
    background:#ddd;
}
li label{
    display:block;
    width:200px;
    line-height:36px;
    font-size:18px;
    cursor:pointer;
}
.content{
    position:relative;
    overflow:hidden;
    width:400px;
    height:100px;
    border:1px solid #999;
    box-sizing:border-box;
    padding:10px;
}
.content1,
.content2{
    display:none;
    width:100%;
    height:100%;
}
.nav1:checked ~ .nav li {
    background:#ddd;
    color:#000;
    
    &:first-child{
        background:#ff7300;
        color:#fff;
    }
}
.nav2:checked ~ .nav li{
    background:#ddd;
    color:#000;
    
    &:last-child{
        background:#ff7300;
        color:#fff;
    }
}
.nav1:checked ~ .content > div{
    display:none;
    
    &:first-child{
    display:block;
    }
}
.nav2:checked ~ .content > div{
    display:none;
    
    &:last-child{
    display:block;
    }
}
.active {
        background:#ff7300;
        color:#fff;
}
.default{
    display:block;
}
</style>

var str="helloworld";
  方法一：用hash
  for(var i=0,hash={};i<str.length;i++){
    if(hash[str[i]]){
      hash[str[i]]++
    }else{
      hash[str[i]]=1;
    }
  }
  console.dir(hash);
方法二：用正则
var arr=str.split("")
  .sort()
  .join("")
  .match(/([a-z])\1*/g)
  .sort(function(a,b){
return b.length-a.length; })
console.log("出现最多的是: "+arr[0][0]
  +"共"+arr[0].length+"次");
var hash={};
  arr.forEach(function(val){
    hash[val[0]]=val.length;
  });
  console.dir(hash);

for(var i = 1; i <= 60 ; i++){
if(i%7 == 0 || i%10 == 7){
console.log(i);
}
}