Add alpha on/off option please

[Riant]

Most times we do not need the alpha setting, if we can set it as disabled or hide the alpha slider bar, that's better, thanks

[linx4200]

Added this feature in 2.4.1. Please upgrade to this latest version. And thanks for your feedback.

Here is the example:

<chrome-picker :value="colors" :disableAlpha="true"></chrome-picker>
<sketch-picker v-model="colors" :disableAlpha="true"></sketch-picker>

[sarkiroka]

I think it would be a good idea to write this into the readme file :)