Page 97 - HTML5

<input type="file" name="fileSubmission" accept="image/x-png,image/gif,image/jpeg" />

Input Validation

HTML input validation is done automatically by the browser based on special attributes on the
input element. It could partially or completely replace JavaScript input validation. This kind of
validation can be circumvented by the user via specially crafted HTTP requests, so it does not
replace server-side input validation. The validation only occurs when attempting to submit the
form, so all restricted inputs must be inside a form in order for validation to occur (unless you're
using JavaScript). Keep in mind that inputs which are disabled or read-only will not trigger
validation.

Some newer input types (like email, url, tel, date and many more ) are automatically validated and
do not require your own validation constraints.

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Required

Use the required attribute to indicate that a field must be completed in order to pass validation.

<input required>

Minimum / Maximum Length

Use the minlength and maxlength attributes to indicate length requirements. Most browsers will
prevent the user from typing more than max characters into the box, preventing them from making
their entry invalid even before they attempt submission.

<input minlength="3">
<input maxlength="15">
<input minlength="3" maxlength="15">

Specifying a range

Use min and max attributes to restrict the range of numbers a user can input into an input of type

number or range

Marks: <input type="number" size="6" name="marks" min="0" max="100" />
Subject Feedback: <input type="range" size="2" name="feedback" min="1" max="5" />

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Match a Pattern

For more control, use the pattern attribute to specify any regular expression that must be matched
in order to pass validation. You can also specify a title, which is included in the validation

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