HTML5是否可以在旧浏览器中使用？

Question

I want to know that does HTML 5 validations works in old browsers if yes then its great and if not then why HTML validations are developed its a high security risk because if a beginner rely on these validations then it may be harmful for his/her. I added more tags because I want to know the reason behind development of HTML 5 Validations Thank you

Answer 1

I want to know that does HTML 5 validations works in old browsers

No. New features don't work in old browsers.

if yes then its great and if not then why HTML validations are developed its a high security risk because if a beginner rely on these validations then it may be harmful for his/her.

It is no more of a security risk than client side JavaScript validation.

Any form of client side validation is there as a convenience for the user, not for security.

If you want security then you must use server side validation. You can't perform this until the form has been submitted (and then you need to send an error page back to the browser).

I want to know the reason behind development of HTML 5 Validations

People have used client side validation for years (because making things more convenient for users is a good thing). Having a method to do it baked in to HTML makes it easier to do and gives a consistent UI.

Answer 2

A relative easy way to check HTML5 support in browsers via Jquery as

 function supportsFormaction() {
    var input = document.createElement("input"); // create an element in memory
    return "formAction" in input; // check if the browser supports the attribute
}

Now the return of this function would be boolean as

• True: Supported
• False Not Supported

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Logic : FormAction is a HTML5 property and thus will give false when used in browsers not supporting HTML5.