Bug: Backspace in input type="number" behaves badly in Blink #7253

STRML · 2016-07-12T22:58:16Z

This appears to have been introduced in a new Chrome version, but I can't find any reference to where.

Affected/Tested Browsers (OS X):

Chrome 51.0.2704.106 (64-bit)
Opera 39.0.2256.15

Unaffected Browsers:

Safari 9.1
Firefox 49

Backspacing in an input element with value or defaultValue set causes some very odd behavior. Once a decimal point is gone, it can't easily be re-added.

Example:

In this example, I simply backspaced twice. On the second backspace, when I expect 3. to be showing, the input instead reads 3 and the cursor has moved to the beginning. The next two jumps are my attempts to add another decimal point.

Fiddle: https://jsfiddle.net/kmqz6kw8/

Tested with React 15.2.

Notes: This only occurs when value or defaultValue is set. If neither is set, the input behaves properly. We are currently working around this issue by (unfortunately) setting the input value on componentDidMount via a ref.

The text was updated successfully, but these errors were encountered:

zpao · 2016-07-12T23:48:46Z

😢 Thanks for filing. I confirmed 15.2.1 is still broken too. Most likely more fallout from #6406.

jimfb · 2016-07-18T16:13:12Z

Number inputs are broken in React, due to #6556, which was filed before #6406 was merged. You're going to see the same problem with email inputs (as per #6368, which is basically the same issue, again filed before #6406 was merged).

It is entirely possible that #6406 exposes that bug for defaultValue, but the bug was always there in the React core and was always visible for controlled inputs.

This has been broken in React for as long as I can remember:

var NumberInput = React.createClass({
  getInitialState: function() { return {value: 3.14}; },
  render: function() {
    return <input type="number" value={this.state.value} onChange={(e)=>{this.setState({value: e.target.value});}} />;
  }
});

ReactDOM.render(
  <NumberInput />,
  document.getElementById('container')
);

A workaround is to set type=text and do manual value filtering to ensure that only numbers are entered into the textbox. This has the downside that you don't get the numeric keyboard on mobile, but we'll need to figure out a solution to #6556 to handle that properly.

STRML · 2016-07-18T16:19:14Z

@jimfb Understood, it's very frustrating that there is no way to get the raw value out of an <input type="number">. I think, though, that it deserves some investigation into why this bug does not manifest in Firefox, as I believe it still follows the spec on that one.

jimfb · 2016-07-18T16:30:50Z

@STRML That's because Firefox doesn't fire an onChange if the input's value is invalid. It's an interesting way of sidestepping the issue in the common case, since the onChange behavior is presumably undefined when the input is in an illegal state.

stephenjwatkins · 2016-07-21T18:13:07Z

This has been broken in React for as long as I can remember

Based on these two codepens, this bug was introduced in 15.2.0.

15.1.0: http://codepen.io/stephenjwatkins/pen/GqxGWJ [works]
15.2.0: http://codepen.io/stephenjwatkins/pen/yJpWQk [doesn't work]

jimfb · 2016-07-21T18:36:33Z

Wow, did Chorme just release an update? I'm 98% positive that codepen would not have worked a week or two ago.

It looks like Chrome will now retain the "." when the user does a input.value=3

The fiddles in #6556 are now all behaving in a "nicer" way now. Looks like the ball is back in our court.

How much you want to bet that Chrome fixed this because of React?

STRML · 2016-07-21T19:49:03Z

Still broken in 52.0.2743.82 (64-bit), are you seeing this working with 15.2.0?

jimfb · 2016-07-21T20:18:23Z

What is still broken? I'm talking about the fiddles in #6556. Do those still look broken to you?

STRML · 2016-07-21T21:19:52Z

Yes - on Chrome 52

Edit: I see what you mean, the following sequence now behaves properly:

Type 3 - onInput calls back with '3'
Type . - onInput calls back with '3', previously ''
Type 1, onInput calls back with '3.1'

nhunzaker · 2016-07-26T11:54:50Z

Confirmed for me on:
Version 52.0.2743.82

Specifically, it looks like input.value is lopping off the decimal point:

To reproduce:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Chrome Backspace Issue</title>
  </head>
  <body>
    <div id="container"></div>

    <script src="../../build/react.js"></script>
    <script src="../../build/react-dom.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.24/browser.min.js"></script>

    <script type="text/babel">
      var NumberInput = React.createClass({
        render: function() {
          return <input type="number" defaultValue={ this.props.defaultValue } />;
        }
      });

      ReactDOM.render(
        <NumberInput defaultValue={3.14} />,
        document.getElementById('container')
      );
    </script>
  </body>
</html>

If you backspace to clear the 14 in 3.14, Chrome is reporting input.value to be 3, instead of 3..

Do I have this right? And should uncontrolled inputs even assign values to begin with?

nhunzaker · 2016-07-26T12:00:35Z

Would it be crazy to consider not emitting changes for invalid input? In the case I've detailed above, the stepMismatch validation returns:

nhunzaker · 2016-07-27T01:16:07Z

Ahhhh interesting. Maybe I was just in the dark, but assigning defaultValue causes side-effects on value. It seems to trigger validation on value.

Check out this Codepen:

http://codepen.io/nhunzaker/pen/zBaokp

This covers uncontrolled inputs, but controlled inputs follow different rules and seem to rely on value, which always reports 3 instead of 3. for me.

I've sent out a PR here:

#7359

nhunzaker · 2016-07-27T01:35:13Z

@jimfb You mentioned:

That's because Firefox doesn't fire an onChange if the input's value is invalid. It's an interesting way of sidestepping the issue in the common case, since the onChange behavior is presumably undefined when the input is in an illegal state.

This seems ideal to me: to trade off limiting change exposure for the sake of stable inputs. Is there any interest in moving towards this?

jimfb · 2016-07-27T03:18:01Z

@nhunzaker Sorry, I'm on hackamonth, haven't really been following these threads super closely.

We can't mimic Firefox's behavior, because we can differentiate between the user clearing their text input and an invalid value, AFAIK.

However, I think Chrome fixed their inputs to work correctly, so this class of issues is now fixable. We would almost certainly be interested in a PR. I'll pass this off to @zpao @spicyj and @gaearon.

nhunzaker · 2016-07-27T11:07:33Z

No worries, sounds fun!

If there's a quick reference point, could you reveal more about the Chrome fix? What was actually broken?

jimfb · 2016-07-27T14:29:54Z

@nhunzaker I don't know any quick reference points other than #6556, but the basic problem was that we couldn't get the actual input value (as entered by the user) when the input was in an invalid state (eg. as the user is typing "3.14", there is an illegal intermediate state "3.") and setting the last known legal value would remove the decimal point. Firefox's fix was to not fire onInput for illegal states, Chrome's fix was to not remove the decimal if the value is approximately the same ("3" instead of "3.").

You'll need to do a little digging to figure out the exact behaviors of the various browsers and figure out what a good fix would look like. I don't know the answer off the top of my head, but it looks like things are now sufficiently fixed on the browser's end, so this should be fixable now in React.

FWIW, it may be worth tracking keystrokes and cursor events and paste events, and maintain a perfect shadow state. Since we don't have to deal with non-numeric-ish characters, we don't need to worry about foreign languages (which is where all the input edge cases come from). I think this would allow us to simulate what the browser would do (allow us to know what value is actually in the text box) and sidestep all the weirdness of the type=number spec. Anyway, I'll let you guys figure that out.

nhunzaker · 2016-07-29T00:40:55Z

Okay! So it looks like the issue here is that value is being assigned using the standard React method of updating attributes when the props get passed in here:

https://github.com/facebook/react/blob/master/src/renderers/dom/shared/ReactDOMComponent.js#L926

There is some logic in ReactDOMInput to prevent duplicate values from being assigned here:

https://github.com/facebook/react/blob/master/src/renderers/dom/client/wrappers/ReactDOMInput.js#L201-L210

Unfortunately the new value has already been assigned.

So my first quick hack was to add an exception for value assignment so that it never sets the value attribute if it hasn't changed:

master...nhunzaker:nh-chrome-backspace

I don't really know why this works. I didn't think node.setAttribute('value', value) was meaningful. Still, it fixes all of the issues I've encountered.

nhunzaker · 2016-07-29T00:46:05Z

Here's a quick GIF:

Now it looks like I was dumb and pushed this update to the uncontrolled input fix I sent out here:

#7359

I'll work on getting those tests to pass until we can figure out what to do.

nhunzaker · 2016-07-29T01:13:11Z

Okay. I've polished up #7359. It fixes all issues with uncontrolled and controlled inputs that I have encountered.

I'll put in some extra time to manually test this tomorrow. I'm still struggling to add automated test coverage for these quirks.

nhunzaker · 2016-07-29T01:48:29Z

Here are the cases that I'm covering, using the following code as a test case:

https://gist.github.com/nhunzaker/923efbaddca16ae2384b547555157f61

Do not drop off the decimal place when backspacing

This happens because React sees "3." and tries to compare it against "3". Since it's a string comparison, these are always different.

before:

after:

Do not clear on bad input

This is sort of correct. This works because I'm doing parseInt(input.value) || 0. This makes NaN fallback to 0 if the number isn't recognized. This may require some documentation updating on best practices (or we should talk about it).

before:

after:

Do not "expand" values

This happens because parseFloat will parse "3e1" into 30. React did comparison based on string values, and "3e1" is always different than "30":

before:

after:

Pretty neat! Anything else I've missed?

ccorcos · 2016-09-20T23:14:49Z

I would suggest going one of two ways:

Treat value and onChange just like with a text input. Leave it up to the developer to validate input, format, and prevent invalid numbers, etc. I've created all the validators I want and everything works great for a text input, but then I don't get the number pad on mobile...
Prevent invalid input and let the developer handle the edge cases for "12e", "-", and ".". Meanwhile, do not allow multiple ".", "-", or "e". And enforce "-" must always be at the beginning. This is effectively what I've created with my logic for the text input.

martin-svk · 2016-11-18T17:44:29Z

What is the current state of this issue?

nhunzaker · 2016-11-19T00:10:36Z

I have an outstanding PR here:
#7359

~~Looks like it's now in conflict with master. I'll address those conflicts.~~

Update: Sorry. Looks like something on CI. Upstreamed anyway.

STRML · 2016-11-20T19:29:56Z

Spam again... Seen a lot of this lately

On Nov 20, 2016 1:27 PM, "qagiux" notifications@github.com wrote:

Gonna do the first half of this in https://goo.gl/JBljdR

—
You are receiving this because you were mentioned.
Reply to this email directly, view it on GitHub
#7253 (comment),
or mute the thread
https://github.com/notifications/unsubscribe-auth/ABJFP7sCqRcqL6lHOT7LfnoSlIIRQrJYks5rAJ8sgaJpZM4JK6Nl
.

nksfrank · 2017-03-09T10:28:33Z

What's the state of this issue? We are still encountering this on v15.4.2

nhunzaker · 2017-03-09T11:49:30Z

@nksfrank I believe the plan is to ship this with 15.5:
#8854

nhunzaker · 2017-03-27T17:57:08Z

This should be addressed in 15.5, now that we've merged the number input PR:
#7359 (comment)

I'll leave this ticket open, I don't know what the protocol is on closing tickets before a release with a fix has been published.

nhunzaker · 2017-03-27T23:45:13Z

cc @aweary I just realized I can't close this :(

STRML · 2017-04-07T22:27:57Z

Fixed! https://jsfiddle.net/09Lxxzn9/1/

Thanks for your hard work @nhunzaker.

zpao added the Type: Regression label Jul 12, 2016

syranide mentioned this issue Jul 18, 2016

<input type='number' defaultValue={someValue}/> is not working correctly in Chrome #7297

Closed

nhunzaker mentioned this issue Jul 27, 2016

Fix Chrome number input backspace and invalid input issue #7359

Merged

whitphx mentioned this issue Aug 7, 2016

input[type=number]の挙動がおかしい問題 asha-nepal/AshaFusionCross#91

Closed

This was referenced Aug 11, 2016

Use an ordered property list for inputs, fix some Chrome number input issues #7474

Closed

HTML5 number input uncontrolled mode issues when changing defaultValue #7507

Closed

keyz mentioned this issue Aug 23, 2016

input Unable to enter a decimal #7545

Closed

nhunzaker mentioned this issue Sep 16, 2016

Fix uncontrolled input decimal point "chopping" on number inputs, and validation warnings on email inputs #7750

Merged

aweary mentioned this issue Sep 20, 2016

deleting decimal values in number inputs #7781

Closed

martin-svk mentioned this issue Sep 23, 2016

Problems when changing value of uncontrolled number input in Chrome #7799

Closed

gaearon mentioned this issue Oct 10, 2016

"Composition vs Inheritance" and "Lifting State Up" #7920

Merged

davidkpiano mentioned this issue Oct 28, 2016

When a 'type=number' Control's value has its last decimal removed, cursor is placed at the beginning of input. davidkpiano/react-redux-form#493

Closed

aweary mentioned this issue Nov 5, 2016

Number Input with defaultValue does not accept decimal input #8211

Closed

STRML closed this as completed Apr 7, 2017

chrisdieckhaus mentioned this issue Jan 8, 2018

Issue #11827 Fix ShadowDOM input bug with setDefaultValue #11986

Closed

2 tasks

jeanmaried mentioned this issue Aug 7, 2018

Number field doesn't accept periods for decimal/floats. Not able to save Content Type entry that has number fields strapi/strapi#1697

Closed

gaearon mentioned this issue Aug 31, 2018

React Fire: Modernizing React DOM #13525

Closed

vcanales mentioned this issue Dec 17, 2019

Controlled numeric input gets cleared when unfocused #17609

Open

jameslahm mentioned this issue Aug 15, 2020

fix: synchronize focused email input on blur to avoid check validity when inputting #19621

Closed

vordgi mentioned this issue Aug 17, 2024

Keep value of controlled number fields upon action #30737

Closed

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Bug: Backspace in input type="number" behaves badly in Blink #7253

Bug: Backspace in input type="number" behaves badly in Blink #7253

STRML commented Jul 12, 2016 •

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zpao commented Jul 12, 2016

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jimfb commented Jul 18, 2016

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STRML commented Nov 20, 2016

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nhunzaker commented Mar 27, 2017

STRML commented Apr 7, 2017

Bug: Backspace in input type="number" behaves badly in Blink #7253

Bug: Backspace in input type="number" behaves badly in Blink #7253

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nhunzaker commented Jul 29, 2016

nhunzaker commented Jul 29, 2016 • edited Loading

Do not drop off the decimal place when backspacing

Do not clear on bad input

Do not "expand" values

ccorcos commented Sep 20, 2016

martin-svk commented Nov 18, 2016

nhunzaker commented Nov 19, 2016 • edited Loading

STRML commented Nov 20, 2016

nksfrank commented Mar 9, 2017

nhunzaker commented Mar 9, 2017

nhunzaker commented Mar 27, 2017

nhunzaker commented Mar 27, 2017

STRML commented Apr 7, 2017

STRML commented Jul 12, 2016 •

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