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**26.1 Introduction to Linear Search in JavaScript**

JavaScript is an effective scripting language that can be used to perform search operations on the web. off course, it has to work with server-side programming languages such as Java and CGI to be effective. However, you will learn simple search algorithm here using JavaScript.

**26.2 Performing Linear Search**

In this lesson, we will learn how to write a script to perform a linear search for an array that consists of integers. We employ the If operator to compare the search value entered by the user and each number in the array. If the search value is equal to the number concern, it will return the position of that number in the array (which is actually the value of the subscript plus 1, as the subscript of the array starts with 0). we need to use the function parseInt to convert the value of the subscript into a numeric value so that it can perform arithmetic operation. We also use the logical operators for and if to perform the search operation.

The following is the script:

<head>

<title>Performing Linear Search of an Array</title><script type = “text/javascript”>

<!–

var a = [4,8,13,17,19,22,25,35,39,41,49,53,59,67,69,75,78,83,90,99]

function SearchArray()

{

var searchNum = searchForm.inputVal.value;

var position = Search( a, parseInt( searchNum ) );

if ( position != -1 )

searchForm.result.value =

“The number is in position ” +( parseInt(position)+1);

else

searchForm.result.value = “The number is not found”;

}

// Search “theArray” for the specified “key” value

function Search( theArray, key )

{

for ( var n = 0; n < theArray.length; ++n )

if ( theArray[ n ] == key )

return n;

return -1;

}

// –>

</script>

</head>

<body>

<h1>Perfoming Linear Search</h1>

<form name = “searchForm” action = “”>

<p>Enter an Integer between 0 and 100 (excluding 0 and 100)<br />

<input name = “inputVal” type = “text” />

<input name = “search” type = “button” value = “Search”

onclick = “SearchArray()” /><br /></p>

<p>Result<br />

<input name = “result” type = “text” size = “30” /></p>

</form>

</body>

</html>

Click Example 26.1 to view the actual output.