UnOpacity

UnOpacity lets you use the opacity property in older Internet Explorer.

/* before */

.figure {
    opacity: .5;
}

/* after */

.figure {
    filter: alpha(opacity=50);
}

Usage

Add UnOpacity to your build tool:

npm install postcss-unopacity --save-dev

Node

Use UnOpacity to process your CSS:

require('postcss-unopacity').process(YOUR_CSS, { /* options */ });

PostCSS

Add PostCSS to your build tool:

npm install postcss --save-dev

Use UnOpacity as a plugin:

postcss([
    require('postcss-unopacity')({ /* options */ })
]).process(YOUR_CSS, /* options */);

Gulp

Add Gulp PostCSS to your build tool:

npm install gulp-postcss --save-dev

Use UnOpacity in your Gulpfile:

var postcss = require('gulp-postcss');

gulp.task('css', function () {
    return gulp.src('./src/*.css').pipe(
        postcss([
            require('postcss-unopacity')({ /* options */ })
        ])
    ).pipe(
        gulp.dest('.')
    );
});

Grunt

Add Grunt PostCSS to your build tool:

npm install grunt-postcss --save-dev

Use UnOpacity in your Gruntfile:

grunt.loadNpmTasks('grunt-postcss');

grunt.initConfig({
    postcss: {
        options: {
            use: [
                require('postcss-unopacity')({ /* options */ })
            ]
        },
        dist: {
            src: '*.css'
        }
    }
});

Options

browsers

Type: String | Array
Default: null

A list of browsers you want to target in your project. If no older Internet Explorer browsers are specified, this plugin will not make any changes to your CSS.

require('postcss-unopacity')({
  browsers: ["> 1%", "last 2 versions", "Firefox ESR"]
})

This may also be defined in package.json.

{
  "browserslist": ["> 1%", "last 2 versions", "Firefox ESR"]
}

method

Type: String
Default: 'replace'

replace

Replace any opacity property with a fallback.

/* before */

.figure {
    opacity: .5;
}

/* after */

.figure {
    filter: alpha(opacity=50);
}

copy

Copy any opacity property with a fallback.

/* before */

.figure {
    opacity: .5;
}

/* after */

.figure {
    filter: alpha(opacity=50);
    opacity: .5;
}

warn

Warn when an opacity property is used.

prefixed

Type: Boolean
Default: false

true

Use an -ms-filter property as a fallback.

/* before */

.figure {
    opacity: .5;
}

/* after */

.figure {
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
}

false

Use a filter property as a fallback.

/* before */

.figure {
    opacity: .5;
}

/* after */

.figure {
    filter: alpha(opacity=50);
}