An example of array usage in JavaScript _javascript techniques

This example describes the array usage in JavaScript. Share to everyone for your reference. The specific analysis is as follows:

The array objects in JavaScript are arrays, first a dynamic array, and a super complex like C #, Java "arrays, lists, hashmap/dictionary", and so on.

Array arrays

How to use:

Example 1:

var citys = new Array ();
Create an Array object without initializing the length, dynamic 
citys[0] = ' Shanghai '; 
Citys[1] = ' Beijing '; 
CITYS[2] = ' Shenzhen ';
for (var i=0; i< citys.length; i++) { 
  alert (citys[i)); 

Example 2 (recommended):

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

Forin Traverse Array Array

var arr=[' Hani ', ' Zhuang ', ' Manchu ', ' floating clan ']; 
For (var item in arr) { 
  alert (item+ ' = = ' +arr[item]); 
}

Array key value pairs

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]); 
}

Traversal array key value pairs

Forin Cycle

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

Through the object. Key

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

method to pass a 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); 
}
Of course Forin also can, but trouble for
(Var item in Code.children) { 
  alert (item+ ' >> ' +code.children[item].name+ ' = = = ' + code.children[item].age); 
}

Array comparison

Customizing a generic 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 in JavaScript sort ()

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 help you with your JavaScript programming.