Example analysis of Array usage in Javascript_javascript skills

The examples in this article describe the usage of Array in Javascript. Share it with everyone for your reference. The specific analysis is as follows:

The Array object in JavaScript is an array. First of all, it is a dynamic array, and it is a super complex like "array, List, HashMap/Dictionary" in C# and Java.

Array array

How to use:

Example 1:

var citys = new Array();
//创建数组对象，无需初始化长度，动态 
citys[0] = '上海'; 
citys[1] ='北京'; 
citys[2] = '深圳';
for(var i=0; i< citys.length; i++){ 
  alert(citys[i]); 
}

Example 2 (recommended):

var arr=[10,true,'哇咔咔']; 
for(var i=0;i<arr.length;i++){ 
  alert(arr[i]); 
}

forin traverses the Array array

var arr=['哈尼族','壮族','满族','漂族']; 
for(var item in arr){ 
  alert(item+'===='+arr[item]); 
}

Array key-value pair

How to use

For example:

var arr=new Array(); 
arr["name"]='Jack'; 
arr["age"]=28; 
arr["gender"]='fale'; 
arr["height"]=180; 
for(var item in arr){ 
  alert(item+'===='+arr[item]); 
}

Traverse Array key-value pairs

forin loop

var arr={name:'James',age:28}; 
for(var item in arr){ 
  alert(item+'==='+arr[item]); 
}

Pass object.key

var arr={name:'James',age:28}; 
alert(arr.name); 
alert(arr.age);

Method passing value

function f1(s){ 
  alert(s.name); 
  alert(s.age); 
} 
f1({name:'Rose',age:20});

Special guy

Example 1:

var arr=[{name:'James',age:19},{name:'Rose',age:18},{name:'Max',age:20}]; 
for(var i=0;i<arr.length;i++){ 
  alert(arr[i].name+'==='+arr[i].age); 
}

Example 2:

var code={name:'Max',children:[{name:'jack',age:20},{name:'rose',age:18}]}; 
alert(code.name); 
for(var i=0;i<code.children.length;i++){ 
  alert(code.children[i].name+'>>'+code.children[i].age); 
}
//当然forin也可以，但麻烦
for(var item in code.children){ 
  alert(item+'>>'+code.children[item].name+'==='+code.children[item].age); 
}

Array comparison

Customize a common comparison method

function max(arr,compare){ 
  var m=arr[0]; 
  for(var i=1;i<arr.length;i++){ 
 if(compare(arr[i],m)){ 
   m=arr[i]; 
 } 
  } 
  return m; 
}
var s1=max([12,32,33,100,8],function(n1,n2){ 
  return n1>n2; 
}); 
alert(s1);
var s2=max(["aa","bbbb","ccc"],function(n1,n2){ 
  return n1.length>n2.length; 
});
alert(s2);

Comparison method sort() in Javascript

Example 1:

var arr=[23,12,56,200,45]; 
arr.sort(function(n1,n2){ 
  return n1>n2; 
}); 
alert(arr);
var arrStr=["aa","bbb","cccc"]; 
arrStr.sort(function(n1,n2){ 
  return n1.length>n2.length; 
}); 
alert(arrStr);

Example 2:

var arr=[{name:'Bob',age:100},{name:'Tom',age:23},{name:'Rose',age:78}]; 
arr.sort(function(n1,n2){ 
  return n1.age>n2.age; 
}); 
for(var i=0;i<arr.length;i++){ 
  alert(arr[i].name);//Tom,Rose,Bob 
}

I hope this article will be helpful to everyone’s JavaScript programming design.