Validating charater strings using javascript

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You want to be sure that your visitors enter data into the HTML fields you have "required" for a valid submission.

Below is the Java Script code to perform this basic check to see if a given HTML input is empty or not.

The last example includes parentheses which are used as a memory device.

The match made with this part of the pattern is remembered for later use, as described in Using parenthesized substring matches.

Java Script also lets you display helpful alerts to inform the user what information they have entered incorrectly and how they can fix it.

In this lesson we will be reviewing some basic form validation, showing you how to check for the following: This lesson is a little long, but knowing how to implement these form validation techniques is definitely worth the effort on your part.

This chapter describes Java Script regular expressions.

We’ll say that a red rectangle holds a weak password, orange medium, and green a strong password.The HTML behind this would look something like the following: Moving beyond the basic Angular JS stuff, lets get down to the good stuff.We’re going to make use of two different Reg Ex validation strings.Remember to check out Tizag's HTML forms lesson if you need to brush up on your form knowledge.This has to be the most common type of form validation.This regular expression pattern is very useful to implement a strong and complex password.

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