Javascript Array Object
What is an Array?
Create an Array
Access an Array
Modify Values in an Array
Examples
The array object is used to store multiple values in a single variable.
What is an Array?
An array is a special variable that can hold more than one value at a time.
Each element in the array has it's own ID so that it can be easily accessed
Create an Array
An array can be defined in three ways.
1.
var myCars=new Array();
//create a new array with no elements
//new Array(n); will create a new array of length n
myCars[0]="saab";
myCars[1]="volvo";
myCars[2]="BMW";
2.
var myCars=new Array("saab","volvo","BMW");
//create a new array with the specified elements
3.
var myCars=["saab","volva","BMW"];
//2 and 3 are functionally equivalent
Access an Array
you can refer to a perticular element in an array by reffering to the name of the array and the index number.
the index number starts at 0.
document.write(myCars[0]);
output: saab
Modufy values in an array
to modify a value in an array, just specify a new value for the element at the given index.
myCars[0]="opel" //overwrite the current value of mycars[0]
document.write(myCars[0]);
output: opel
Examples
how to create an array, assign values to it, and write the values to output.
<html>
<body>
<script type="text/javascript">
var myCars = new Array();
myCars[0] = "saab";
myCars[1] = "volvo";
myCars[2] = "BMW";
for(i=0;i<myCars.length;i++)
{
document.write(myCars[i]+"<br/>");
}
</script>
</body>
</html>
how to use a for...in statement to loop through the elements of an array.
<html>
<body>
<script type="text/javascript">
var x;
var mycars=new Array();
mycars[0]="saab";
mycars[1]="volvo";
mycars[2]="BMW";
for(x in mycars)
{
document.write(mycars[x]+"<br/>");
}
</script>
</body>
</html>
how to join two arrays
<html>
<body>
<script type="text/javascript">
var parants=["jani","tove"];
var children=["cecilie","lone"];
var family=parants.concat(childrenn);
document.write(family);
</script>
</body>
</html>
how to join three arrays
<html>
<body>
<script type="text/javascript">
var parants=["jani","tove"];
var children=["cecilie","lone"];
var brothers=["stale","kai jim","borge"];
var family=parents.concat(brothers,children);
</script>
</body>
</html>
how to join all elements of an array into a string
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.join()+"<br/>");
document.write(fruite.join("+")+"<br/>");
document.write(fruite.join("and"));
</script>
</body>
</html>
how to remove the last element of an array
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.pop()+"<br/>");
document.write(fruits+"<br/>");
document.write(fruits.pop()+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to add new element to the end of an array
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.push("kiwi")+"<br/>");
document.write(fruits.push("Lemon","pineapple")+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to reverse the order of the elements in an array
<html>
<body>
<script type="text/javascript">
var fruits=["Banana","orange","apple","mango"];
document.write(fruits.reverse());
</script>
</body>
<//html>
how to remove the first element of an array
<html>
<body>
<script type="text/javascript">
var fruits=["Banana","orange","apple","mango"];
document.write(fruits.shift()+"<br/>");
document.write(fruits+"<br/>");
document.write(fruits.shift()+"<br/>);
document.write(fruits+"<br/>");
</script>
</body>
</html>
how to use slice to select elements from an array.
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.slice(0,1)+"<br/>");
document.write(fruits.slice(1)+"<br/>");
document.write(fruits.slice(-2)+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to use sort().
how to sort alphabetically and ascending
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.sort());
</script>
</body>
</html>
how to sort numarically and ascending
<html>
<body>
<script type="text/javascript">
function sortnumber(a,b)
{
return a-b;
}
var n=["10","5","40","25","100","1"];
document.write(n.sort(sortnumber));
</script>
</body>
</html>
how to sort() numerically and descending.
<html>
<body>
<script type="text/javascript">
function sortnumber(a,b)
{
return b-a;
}
var n=["10","5","40","25","100","1"];
document.write(n.sort(sortnumber));
</script>
</body>
</html>
how to use slice() to add an element to the second position in an array
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write("Removed:"+fruits.splice(2,0."Lemon")+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to convert an array to a string
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.toString());
</script>
</body>
</html>
how to add new elements to te begining of an array
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.unshift("kiwi")+"<br/>");
document.write(fruits.unshift("Lemon","pineapple")+"<br/>");
document.write(fruits);
</script>
<p><b>Note:</b> The unshift() method does not work properly in internet explorer, it only returns undefined!</p>
</body>
</html>
What is an Array?
Create an Array
Access an Array
Modify Values in an Array
Examples
The array object is used to store multiple values in a single variable.
What is an Array?
An array is a special variable that can hold more than one value at a time.
Each element in the array has it's own ID so that it can be easily accessed
Create an Array
An array can be defined in three ways.
1.
var myCars=new Array();
//create a new array with no elements
//new Array(n); will create a new array of length n
myCars[0]="saab";
myCars[1]="volvo";
myCars[2]="BMW";
2.
var myCars=new Array("saab","volvo","BMW");
//create a new array with the specified elements
3.
var myCars=["saab","volva","BMW"];
//2 and 3 are functionally equivalent
Access an Array
you can refer to a perticular element in an array by reffering to the name of the array and the index number.
the index number starts at 0.
document.write(myCars[0]);
output: saab
Modufy values in an array
to modify a value in an array, just specify a new value for the element at the given index.
myCars[0]="opel" //overwrite the current value of mycars[0]
document.write(myCars[0]);
output: opel
Examples
how to create an array, assign values to it, and write the values to output.
<html>
<body>
<script type="text/javascript">
var myCars = new Array();
myCars[0] = "saab";
myCars[1] = "volvo";
myCars[2] = "BMW";
for(i=0;i<myCars.length;i++)
{
document.write(myCars[i]+"<br/>");
}
</script>
</body>
</html>
how to use a for...in statement to loop through the elements of an array.
<html>
<body>
<script type="text/javascript">
var x;
var mycars=new Array();
mycars[0]="saab";
mycars[1]="volvo";
mycars[2]="BMW";
for(x in mycars)
{
document.write(mycars[x]+"<br/>");
}
</script>
</body>
</html>
how to join two arrays
<html>
<body>
<script type="text/javascript">
var parants=["jani","tove"];
var children=["cecilie","lone"];
var family=parants.concat(childrenn);
document.write(family);
</script>
</body>
</html>
how to join three arrays
<html>
<body>
<script type="text/javascript">
var parants=["jani","tove"];
var children=["cecilie","lone"];
var brothers=["stale","kai jim","borge"];
var family=parents.concat(brothers,children);
</script>
</body>
</html>
how to join all elements of an array into a string
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.join()+"<br/>");
document.write(fruite.join("+")+"<br/>");
document.write(fruite.join("and"));
</script>
</body>
</html>
how to remove the last element of an array
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.pop()+"<br/>");
document.write(fruits+"<br/>");
document.write(fruits.pop()+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to add new element to the end of an array
<html>
<body>
<script type="text/javascript">
var fruites=["Banana","orange","apple","mango"];
document.write(fruits.push("kiwi")+"<br/>");
document.write(fruits.push("Lemon","pineapple")+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to reverse the order of the elements in an array
<html>
<body>
<script type="text/javascript">
var fruits=["Banana","orange","apple","mango"];
document.write(fruits.reverse());
</script>
</body>
<//html>
how to remove the first element of an array
<html>
<body>
<script type="text/javascript">
var fruits=["Banana","orange","apple","mango"];
document.write(fruits.shift()+"<br/>");
document.write(fruits+"<br/>");
document.write(fruits.shift()+"<br/>);
document.write(fruits+"<br/>");
</script>
</body>
</html>
how to use slice to select elements from an array.
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.slice(0,1)+"<br/>");
document.write(fruits.slice(1)+"<br/>");
document.write(fruits.slice(-2)+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to use sort().
how to sort alphabetically and ascending
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.sort());
</script>
</body>
</html>
how to sort numarically and ascending
<html>
<body>
<script type="text/javascript">
function sortnumber(a,b)
{
return a-b;
}
var n=["10","5","40","25","100","1"];
document.write(n.sort(sortnumber));
</script>
</body>
</html>
how to sort() numerically and descending.
<html>
<body>
<script type="text/javascript">
function sortnumber(a,b)
{
return b-a;
}
var n=["10","5","40","25","100","1"];
document.write(n.sort(sortnumber));
</script>
</body>
</html>
how to use slice() to add an element to the second position in an array
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write("Removed:"+fruits.splice(2,0."Lemon")+"<br/>");
document.write(fruits);
</script>
</body>
</html>
how to convert an array to a string
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.toString());
</script>
</body>
</html>
how to add new elements to te begining of an array
<html>
<body>
<script type="text/javascript">
var fruits=["banana","orange","apple","mango"];
document.write(fruits.unshift("kiwi")+"<br/>");
document.write(fruits.unshift("Lemon","pineapple")+"<br/>");
document.write(fruits);
</script>
<p><b>Note:</b> The unshift() method does not work properly in internet explorer, it only returns undefined!</p>
</body>
</html>
1 comment:
nice article for beginners.thank you.
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