Validating a textbox

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The validation functionality uses Javascript code to present an alert to users who have typed in invalid input.Two examples are provided: email address validation and number validation. That is, the form will not be submitted until and unless the user provides valid data for both items. This means that as a programmer, you have the power to supply the exact pattern for the input you desire in any text input field. Again, certain special characters are obviously not allowed. They make use of a pattern matching system to match the input with a certain pattern of data.Well, sometimes a good structured and thought out If statement can suffice, but it can become quite long and cumbersome in the future. By using Regular Expressions this way, you can reduce the chances of getting errors at erratic times. This sub checks the email's format and if it thinks that it matches, it returns True and vice versa.Also, the more tests you are performing, the slower your app might become. For more information regarding Regular Expressions, you are welcome to look at these two MSDN articles: Because it is always easy to learn by doing things practically, you will be creating an app that makes use of Regular Expressions to determine valid input. NET application and design the form to resemble Figure 1. Obviously this only works for the formatting of the email.

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The textbox-validate template is a type of HTML form that is a variant of the textbox.Using regular expressions the entered content can be validated with advanced conditions like the string entered shouldn’t contain spaces, special characters, numbers, uppercase or lowercase etc.Once you learn the art of using regular expressions you can use it with many computer languages.But have to trade off performance on the client side.Please have a look at to have a better control of what you need.

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