Form Validation Example
<html> <body> <script type="text/javascript"> <!-- /* ******************************************************** Javascript Regular Expression Example 24 Fom validation example ******************************************************** */ function calcm( ) { var calForm = document.getElementById('form1'); var pattern1= /^\d\d*\.?\d*$/ ; if (pattern1.test(calForm.inch.value)) { calForm.cm.value = calForm.inch.value *2.54; } else { calForm.cm.value ="Wrong Input"; } } //----> </script> </head> <body> <br> Inch to centimeter conversion <br /> <br /> <form method="post" id="form1" name="form1"> <table> <tbody> <tr> <td><b> Enter inches :</b></td> <td> <input name="inch" size="10"></td> </tr> <tr> <td> <input id="button2" name="button2" value="Calculate cm" onclick="calcm()" type="button"></td> <td> <input name="cm" size="10"> </td> </tr> </tbody></table> </form> </body> </html> |
Try this Example online
You can try this example online at - here .
Under normal conditions, the script gives the following output.
If however, the input is not a valid decimal input, it displays the error as follows.
Notice the pattern used to check a valid decimal input
var pattern1= /^\d\d*\.?\d*$/ ;
One more point to note is that the dot sign is used to match any input which is not a new line. To match actual dot . , we use escaping character "\." . The decimal point is checked using "\.". Without the escaping character it will match "any character except new line".