for...in statements

JavaScript for...in Statements

The for...in statement is used to loop an array or an object's properties.

The code for the for ... in loop executes once for each time, and the elements of the array or the properties of the object are manipulated once.

Grammar:

forinObject) {    execute code here}

A variable is used to specify a variable, which can be an array element or a property of an object.

Instance:

Iterate through the array using the for ... in loop.

for (x in mycars){document.write(mycars[x] + "<br />")} </script></body>
executes one or more statements for each property of an object, or for each element in an array or collection. for ([var] variable in {object | array | collection})
   Statement
actual Parameters
 
 

  
  
 
  
  
 
   Variable 
  
  
  
  
 
  
  
 
   
Must be selected. A variable that can be any property name of object , any index ofarray , or any element of collection. 
 
  
  
  
  
 
  
  
 
   Object 
  
  
  
  
 
  
  
 
   
The JScript object to loop on.
 
  
  
  
  
 
  
  
 
   Array 
  
  
  
  
 
  
  
 
   
The array to loop on. it can be either  a JScript array object or an array of. NET Framework. 
 
  
  
  
  
 
  
  
 Collection 
  
  
  
  
 
  
  
 
   
The collection to loop on. it can be any class that implements the IEnumerable or IEnumerator interface from the. NET Framework. 
 
  
  
  
  
 
  
  
 
   Statement 
  
  
  
  
 
  
  
 
   
Optional. the statement to be executed for each property of object or for each element of array or collection. can be a compound statement. 
 
  
  
 
 
Notes 
 collection. " &NBSP for each cycle of the loop,  variable    Assign  ,  object   's Next property name,  array   Next index or  collection .   you can use &NBSP;  variable    for any statement in the loop to refer to  ,  object    Properties or  , and  array    elements. 
When looping over an object, there is no way to determine or control the order in which the object's member names are assigned to variable. The   for...in statement cannot loop on a member of a non-JScript object, for example,. NET Framework objects. 
The array loops by element order, starting with the smallest index and ending with the largest index.for...in statement accesses only the defined Eleme NTS of the array. " Because jscript   Array    object may be sparse, so    for...in  Statement only accesses elements that are already defined in the array.  jscript   Array    objects can also have a expando property, in which case it is    variable    assigns an array index as the property name.   If the array is a multidimensional. NET Framework Array, only the first dimension is enumerated. 
To cycle through the collection, the elements are assigned to variablein the order in which they appear in the collection.
Example 1The following example illustrates the use of a for ... in statement that uses an object as a related array.  
function ForInDemo1 () {    //Initialize the object.    var obj = {"A": "Athens", "B": "Belgrade", "C": "Cairo"}    //Iterate over the properties and create the string resu Lt.    var s = "" for    (var key in obj)    {        S + = key + ":  " + obj[key];        s + = "\ n";    }    return (s);}
This function returns a string that contains the following:
A:  ATHENSB:  belgradec:  Cairo
for...in statements