How JavaScript validates API constraints and verifies DOM

This article mainly introduces "JavaScript how to verify API constraints and verify DOM" related knowledge, editor through the actual case to show you the operation process, the method of operation is simple and fast, practical, I hope that this "JavaScript how to verify API constraints and verify DOM" article can help you solve the problem.

JavaScript verifies the use of checkValidity in API

Attribute description

CheckValidity () returns true if the input element contains valid data.

SetCustomValidity () sets the validationMessage attribute of the input element.

If the input field contains invalid data, a message is displayed:

CheckValidity () method

OK

Function myFunction () {

Let text = "Value OK"

If (document.getElementById ("id1") .validity.rangeOverflow) {

Text = "Value too large"

}

}

If the number in the input field is less than 100 (the min attribute of the input element), a message is displayed:

RangeUnderflow attribute