React: Support es6 symbols in proptype

Created on 20 Sep 2015 · 13Comments · Source: facebook/react

Would you be open to support es6 symbols in proptype?

At the moment I'm testing them as typeof Symbol() === 'symbol' in custom proptype functions.

starter

Source

dashed

Most helpful comment

We’re still ironing out how we’ll move on with cutting branches on 15.x but once it’s decided I expect this to get in.

gaearon on 15 Apr 2016

👍3

All 13 comments

Here's what I use (not sure if it's the right approach):

function symbol(props, propName, componentName) {
    const prop = props[propName];
    if (prop && (typeof prop !== 'symbol')) {
        return new Error(`[${componentName}]: Expected property ${propName} to be a Symbol, but its actual type is ${typeof prop}.`);
    }
}

symbol.isRequired = function(props, propName, componentName) {
    return props[propName] ?
           symbol(props, propName, componentName) :
           new Error(`[${componentName}]: Property ${propName} is required.`);
};

export default symbol

steve-taylor on 21 Sep 2015

We've generally said no to a lot of custom proptypes checks but this one feels like it's probably ok. In theory it's a 1 line change. However we aren't applying the Symbol transform (which changes all typeof checks) so we'd have to do something similar with the type (already have that in place for RegExps and old browsers) - not hard but just a little bit more work.

Thoughts @sebmarkbage @spicyj

zpao on 21 Sep 2015

Yea. Seems reasonable. The .constructor === Symbol as a fallback is ok. Not ideal since it doesn't work cross-realm but we should use whatever is standard practice among popular polyfills.

sebmarkbage on 21 Sep 2015

Any possibility that this will be added in future versions?

puradox on 30 Mar 2016

Yes, we just never got back to it. If you're interested in working on it, this is something that would make a nice addition in 15.1.

zpao on 30 Mar 2016

👍2

@zpao No one is assigned? I could do a PR for it!

RaitoBezarius on 31 Mar 2016

GitHub doesn’t make it very obvious :cry:

Usually when people start working on a feature they reference it, and it appears in the issue.
You can see the existing PR above:

screen shot 2016-03-31 at 14 20 27

gaearon on 31 Mar 2016

Also, you can't assign issues to people who don't have commit access, making it much harder to communicate that somebody outside the core team is working on it.

zpao on 31 Mar 2016

That's a shame, it seems related to https://github.com/isaacs/github/issues/369 and https://github.com/isaacs/github/issues/100 :/

RaitoBezarius on 31 Mar 2016

Any update on this? I suppose I'll switch to string constants in this one instance, but symbols would've been better!