Definition of valid, invalid and required in HTML5

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Definition of valid, invalid and required

The code is as follows

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The code is as follows:

Input:required, Input:valid, input:invalid{border:0 none; outline:0 none;-webkit-box-shadow:none;-moz-box-shadow: None -ms-box-shadow:none; -o-box-shadow:none; Box-shadow:none;}

In the past, verify the form will be through JS and positive to determine whether the completed content is correct, such as the verification of email.

The appearance of HTML5 provides us with some properties that can be resolved without writing JS and regular.

: Required

must, that input cannot be empty meaning.

: Valid

Effective, that is, when the content is filled to meet the requirements of the trigger.

: invalid

is not valid, that is, when the completed content does not meet the requirements of the trigger.