HTML5 implements form checkbox validation

This article will introduce you to the check box verification of HTML5 forms. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

In the previous article [How does JavaScript implement check box verification of the form], we introduced the method of using js to implement the check box verification of the form. This article will introduce it to you. A way to validate checkboxes, using html5 to validate checkboxes.

1. HTML5 Validation Checkbox

Adding HTML5 validation to a checkbox is actually very simple. All you need to do is include the required attributes: required

<form id="example1" method="POST" >

	<p><input id="field_terms" type="checkbox" required name="terms">
	<label for="field_terms">我接受 <u>条款和条件</u></label></p>
	<span><input type="submit"></span>

</form>

Rendering:

This tells the browser not to Allow form submission. Some (but not all) browsers will recognize and enforce this.

The advantage of HTML5 form validation is that it happens before we call JavaScript, showing instructions and pointing the user to the relevant element.

Text alert messages are completely browser generated and can even be automatically converted to different languages, something that is nearly impossible to do using JavaScript.

The advantage of HTML5 form validation is that it prompts the cause of the problem and does not require a clicked alert window. Moreover, the alert text can also be customized.

2. Custom HTML5 messages

We can use our own defined text messages to display on the browser, but this can only be done through JavaScript Finish. This requires checking the element's validity state yourself and explicitly setting (and clearing) the message:

<form id="example1" method="POST" onsubmit="return checkForm(this);">

	<p><input id="field_terms" onchange="this.setCustomValidity(validity.valueMissing ? &#39;请选择接受条款和条件!&#39; : &#39;&#39;);" type="checkbox" required name="terms">
	<label for="field_terms">我接受 <u>条款和条件</u></label></p>
	<span><input type="submit"></span>

</form>
<script type="text/javascript">
	document.getElementById("field_terms").setCustomValidity("请选择接受条款和条件!");
</script>

The JavaScript block below the form assigns a custom error message to the checkbox when the page loads. We know that the checkbox is unchecked by default, so we need to tell the browser what message to display.

If the checkbox is unchecked and the Submit button is clicked, an alert similar to the example above will be displayed, but with our text instead of the default value.

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