transition shorthand unit lost when level is 2

[hsuanxyz]

Precheck

• Do a quick search and make sure a bug has not yet been reported;
• do a quick check if the bug still exists in the latest patch version;
• finally, be nice and have fun!

Environment

• clean-css version: 4.2.x
• node.js version: v10.0.0
• operating system: darwin x64

Configuration options

var CleanCSS = require('clean-css');
var input = `
.a {
  transition: opacity .3s linear, height 0s ease .3s;
}

.b {
  transition: opacity .3s linear, height 1s ease .3s;
}
`;

var options = {
  compatibility: 'ie9',
  level        : 2,
  inline       : false,
  returnPromise: true,
  sourceMap    : true,
};

new CleanCSS(options).minify(input)
  .then(output => {
    console.log(output.styles)
  });

Input CSS

.a {
  transition: opacity .3s linear, height 0s ease .3s;
}

.b {
  transition: opacity .3s linear, height 1s ease .3s;
}

Actual output CSS

.a{transition:opacity .3s linear,height .3s}.b{transition:opacity .3s linear,height 1s .3s}

Expected output CSS

.a{transition:opacity .3s linear,height  0s ease .3s}.b{transition:opacity .3s linear,height 1s ease .3s}

[hsuanxyz]

input

output

[emilemil1]

Still an issue with transition shorthands.

This:

.test {
    transition: opacity 0s 1s;
}
.test.active {
    transition: opacity 1s 0s;
}

Becomes this (formatted):

.test, .test.active {
    transition: opacity 1s
}

From what I can gather, the issue only seems to occur when one of the arguments (duration or delay) is 0s. What I guess is happening is that because 0s is the default for both duration and delay, clean-css incorrectly removes that part of the shorthand, leaving only the other number which is then interpreted as duration. This is fine if only duration is declared, but not if it's both duration and delay since that changes semantics (unless both are 0s).

[jovilog]

Any progress on this issue?