Method supportedValue should support !important property.

[LvChengbin]

it( 'should support !important property (solid 1px red)', () => {
    expect( supportedValue( 'border', 'solid 1px red !important' ) ).to.be( 'solid 1px red !important' );
} );

it( 'should support !important property (1px solid red)', () => {
    expect( supportedValue( 'border', '1px solid red !important' ) ).to.be( '1px solid red !important' );
} );

I added these two test cases for supportedValue method, and got the output as follow:

✖ should support !important property (solid 1px red)
✔ should support !important property (1px solid red)

✖ should support !important property (solid 1px red)
        Chrome 86.0.4229.3 (Mac OS 10.15.6)
      Error: expected false to equal 'solid 1px red !important'
          at Assertion.assert (webpack://cssvendor/node_modules/expect.js/index.js:96:13 <- tests.webpack.js:8:10305)
          at Assertion.be.Assertion.equal (webpack://cssvendor/node_modules/expect.js/index.js:216:10 <- tests.webpack.js:8:11808)
          at Assertion.<computed> [as be] (webpack://cssvendor/node_modules/expect.js/index.js:69:24 <- tests.webpack.js:8:9695)
          at Context.<anonymous> (webpack://cssvendor/src/supported-value.test.js:83:81 <- tests.webpack.js:29:255519)

This issue makes using 1px solid red !important and solid 1px red !important has different result in jss. To support !important property or at least to provide same result with these two type of format.

I can send a pull request for this if you think it makes sense.

[kof]

Have you figured out why this happens?

[LvChengbin]

@kof

A values ends with !important cannot be added as a property of el.style directly, The !important should be removed before adding or just to use style.setProperty instead.
https://github.com/cssinjs/css-vendor/blob/master/src/supported-value.js#L67

Using 1px solid red can pass check because the string starts with a number which matches the condition !isNaN(parseInt(prefixedValue, 10))
https://github.com/cssinjs/css-vendor/blob/master/src/supported-value.js#L52

[kof]

@LvChengbin @AleshaOleg I think nothing stops us from using el.style.setProperty instead of el.style.property! A PR with this would be appreciated along with this use case as a test

[LvChengbin]

I sent a pull request but failed to pass the test and got error message:

23 08 2020 16:23:19.652:INFO [launcher]: Launching browsers BS_MobileSafari, BS_Opera52, BS_Chrome, BS_Safari, BS_Firefox, BS_InternetExplorer9, BS_InternetExplorer10, BS_InternetExplorer11, BS_Edge13 with concurrency 2
23 08 2020 16:23:19.671:ERROR [launcher]: Cannot load browser "BS_MobileSafari"!
  Error: Password is required.
    at ApiClient.BaseClient (/home/travis/build/cssinjs/css-vendor/node_modules/browserstack/lib/client.js:21:9)
    at ApiClient.ApiBaseClient (/home/travis/build/cssinjs/css-vendor/node_modules/browserstack/lib/api.js:9:13)