HTML5 introduced a new HTML validation concept called constraint validation.

HTML constraint validation is based on:

  • Constraint validation HTML Input Attributes
  • Constraint validation CSS Pseudo Selectors
  • Constraint validation DOM Properties and Methods

Constraint Validation HTML Input Attributes

Attribute Description
disabled Specifies that the input element should be disabled
max Specifies the maximum value of an input element
min Specifies the minimum value of an input element
pattern Specifies the value pattern of an input element
required Specifies that the input field requires an element
type  Specifies the type of an input element
 

Constraint Validation CSS Pseudo Selectors

Selector Description
:disabled Selects input elements with the "disabled" attribute specified
:invalid Selects input elements with invalid values
:optional Selects input elements with no "required" attribute specified
:required Selects input elements with the "required" attribute specified
:valid Selects input elements with valid values



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