Polyfill for reportValidity()

HTMLFormElement-HTMLInputElement.reportValidity.js

/* Copyright (c) 2016 Tobias Buschor https://goo.gl/gl0mbf | MIT License https://goo.gl/HgajeK */

if (!HTMLFormElement.prototype.reportValidity) {
    HTMLFormElement.prototype.reportValidity = function() {
        if (this.checkValidity()) return true;
        var btn = document.createElement('button');
        this.appendChild(btn);
        btn.click();
        this.removeChild(btn);
        return false;
    };
}

if (!HTMLInputElement.prototype.reportValidity) {
    HTMLInputElement.prototype.reportValidity = function(){
        if (this.checkValidity()) return true
        var tmpForm;
        if (!this.form) {
            tmpForm = document.createElement('form');
            tmpForm.style.display = 'inline';
            this.before(tmpForm);
            tmpForm.append(this);
        }
        var siblings = Array.from(this.form.elements).filter(function(input){
            return input !== this && !!input.checkValidity && !input.disabled;
        },this);
        siblings.forEach(function(input){
            input.disabled = true;
        });
        this.form.reportValidity();
        siblings.forEach(function(input){
            input.disabled = false;
        });
        if (tmpForm) {
            tmpForm.before(this);
            tmpForm.remove();
        }
        this.focus();
        this.selectionStart = 0;
        return false;
    };
}

@lukescott
Great Work!
I updated my gist with a similiar polyfill.

• handles Inputs without a form
• extended Native HTMLInputElement
• reused the form.reportValidity-polyfill
• no es6 for ie11
• but it needs some polyfills for ie11 (Array.from, Element-Methods: before, after and remove)
• tested in ie11 but not in old safaris

@nuxodin I think there is a bug. It looks like you still use this.form when it could be undefined. You probably want this:

if (!HTMLInputElement.prototype.reportValidity) {
    HTMLInputElement.prototype.reportValidity = function(){
        if (this.checkValidity()) return true
        var form = this.form;
        var tmpForm;
        if (!form) {
            tmpForm = document.createElement('form');
            tmpForm.style.display = 'inline';
            this.before(tmpForm);
            tmpForm.append(this);
        }
        var siblings = Array.from(form.elements).filter(function(input){
            return input !== this && !!input.checkValidity && !input.disabled;
        },this);
        siblings.forEach(function(input){
            input.disabled = true;
        });
       form.reportValidity();
        siblings.forEach(function(input){
            input.disabled = false;
        });
        if (tmpForm) {
            tmpForm.before(this);
            tmpForm.remove();
        }
        this.focus();
        this.selectionStart = 0;
        return false;
    };
}

Although as far as I know html5 validation doesn't work without a form tag anyway. So it probably isn't necessary to support inputs that aren't inside form tags.

Also the focus() in my implementation is a fallback. The submit/reportValidity already does this. I could probably remove it entirely.

My Polyfill works at least in IE.
I use this.form and if this.form is undefined, I wrap it into a newly created form.
So this.form is always defined.

I don't know exactly how it is in the specification, but validation works without forms in current browsers:
https://jsfiddle.net/7jode1g5/

focus() and selectionstart=0 is needed in IE11

In line 19 you are definingvar tmpForm , but it's already defined 2 lines above.

I recommend wrapping all that code in:

if (typeof HTMLFormElement !== 'undefined') {
 // your polyfill
}

So then it'll be also compatible with server side rendering.

this is the form version, which and seems to work in IE11, and accounts for the case the form has a novalidate attribute, in which case the form would submit.
https://gist.github.com/mcshaz/c65040c11e6daffe356cbedb7ec84ce4

Is there anyway to intercept or listen if reportValidity has been called?