Find Position of Left most Vowel: JavaScript

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Develop and demonstrate a xhtml file which uses javascript program to find the first occurrence or the left most vowel in the user entered string.
Input: A String.
Output: Position of the left most or first occurrence of the vowel in the user entered string.

Video Explaining The JavaScript Code:

YouTube Link: http://www.youtube.com/watch?v=ni3diSb5Y40 [Watch the Video In Full Screen.]


Work Flow:
Step 1: Prompt the user to enter a string, store the user entered string in a variable called str.

Step 2: Convert the string in str to upper case using toUpperCase function. Now the original value of str is lost and its equivalent upper case string has been stored.
Ex: str = str.toUpperCase();

Step 3: Now find the length of the entered string using length function. i.e., variableName.length; Ex: str.length;

Step 4: Using for loop, loop through the string from 0 to the string length(which is calculated in Step 3).

Step 5: Using chatAt function fetch one character at a time from str and store it in variable chr. Ex: chr = str.charAt(i);

Step 6: Now compare the value in chr with upper case vowels: A, E, I, O, U.

Step 7: If chr matches any vowel then break out of for loop.

Step 8: If the value of i after coming out of the for loop, is less than string length then print the value of i which is the position of the left most occurrence of the vowel. If the value of i is greater than or equal to string length, then Vowel not found in the entered string.

Javascrip coding explained in above video:

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<html>
 <head><title>Finding Left most Vowel in the Input String</title></head>
 <body>
	<script type="text/javascript">
	<!--
		var chr = "";
		var str = prompt("Enter the string","");
 
		str = str.toUpperCase();
 
		for(var i = 0; i < str.length; i++)
		{
			chr = str.charAt(i);
 
			if(chr == 'A' || chr == 'E' || chr == 'I' 
                                             || chr == 'O' || chr == 'U')
				break;
		}
 
		if( i < str.length )
			document.write("The position of the
                                           left most vowel is "+(i+1)+"<br />");
		else
			document.write("No vowel found in the entered string");
 
	// -->
	</script>
 
 </body>
</html>

Input/Output:
If Microsoft is the input string, then the position of the first occurrence of vowel is 2. i.e., i.
For Oracle, O is a vowel, so the position is 1.
For Technotip, e is the first vowel, so the position is 2.
For any input which do not have a vowel in it, the above javascript program outputs this statement: No vowel found in the entered string

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4 thoughts on “Find Position of Left most Vowel: JavaScript”

  1. Here’s another way to do the same thing…just less tedious. (Just did this for my assignment @ NSU and decided to share (GS).

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    function first_vowel(input)
    {
    	var pattern=/(A|E|I|O|U)/;
    	var pos=input.search(pattern);	
    	var _hindex=pos+1;
     
    	if(pos > -1)
    	{
    	alert("You entered " + input + " (Case in-sensitive)nn
             The first vowel ( " + input[pos].toString() + " )  
             is located at position " + _hindex.toString() + 
             " when looked atnBut is actually " + pos.toString() + " 
             in the zero based index array");
    	}
    	else
    	 alert("No vowels found");	
    }


  2. @Developer, Thanks a lot for sharing this. I’m glad to know about this logic and I’m sure many students will be helped by your generosity to share it with us. Thanks again.

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