a code for generating all.css

[roeycohen]

hoping that this will save time to the one after me, here's my code for generating the all.css files only with the necessary stuff like font-awsome subsetter app does :)

//sets is the same as the object you pass to fontawesomeSubset

const all_icons = Object.values(sets).flat(1);

const vars = fs.readFileSync('node_modules/@fortawesome/fontawesome-pro/scss/_variables.scss', 'utf8').split('\n')
    .filter(l => l.startsWith('$fa-var-'))
    .map(l => l.match(/\$fa-var-([^:]+): \\([^:]+);/).slice(1, 3)); //[ico, code]

const css = [];
css.push(`/*!
 * Font Awesome Pro 5.15.4 by @fontawesome - https://fontawesome.com
 * License - https://fontawesome.com/license (Commercial License)
 */
.fa, .fab, .fad, .fal, .far, .fas {
    -moz-osx-font-smoothing: grayscale;
    -webkit-font-smoothing: antialiased;
    display: inline-block;
    font-style: normal;
    font-variant: normal;
    text-rendering: auto;
    line-height: 1
}

.fa-lg {
    font-size: 1.33333em;
    line-height: .75em;
    vertical-align: -.0667em
}

.fa-xs {
    font-size: .75em
}

.fa-sm {
    font-size: .875em
}

.fa-1x {
    font-size: 1em
}

.fa-2x {
    font-size: 2em
}

.fa-3x {
    font-size: 3em
}

.fa-4x {
    font-size: 4em
}

.fa-5x {
    font-size: 5em
}

.fa-6x {
    font-size: 6em
}

.fa-7x {
    font-size: 7em
}

.fa-8x {
    font-size: 8em
}

.fa-9x {
    font-size: 9em
}

.fa-10x {
    font-size: 10em
}

.fa-fw {
    text-align: center;
    width: 1.25em
}

.fa-ul {
    list-style-type: none;
    margin-left: 2.5em;
    padding-left: 0
}

.fa-ul > li {
    position: relative
}

.fa-li {
    left: -2em;
    position: absolute;
    text-align: center;
    width: 2em;
    line-height: inherit
}

.fa-border {
    border: .08em solid #eee;
    border-radius: .1em;
    padding: .2em .25em .15em
}

.fa-pull-left {
    float: left
}

.fa-pull-right {
    float: right
}

.fa.fa-pull-left, .fab.fa-pull-left, .fal.fa-pull-left, .far.fa-pull-left, .fas.fa-pull-left {
    margin-right: .3em
}

.fa.fa-pull-right, .fab.fa-pull-right, .fal.fa-pull-right, .far.fa-pull-right, .fas.fa-pull-right {
    margin-left: .3em
}

.fa-spin {
    -webkit-animation: fa-spin 2s linear infinite;
    animation: fa-spin 2s linear infinite
}

.fa-pulse {
    -webkit-animation: fa-spin 1s steps(8) infinite;
    animation: fa-spin 1s steps(8) infinite
}

@-webkit-keyframes fa-spin {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg)
    }
    to {
        -webkit-transform: rotate(1turn);
        transform: rotate(1turn)
    }
}

@keyframes fa-spin {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg)
    }
    to {
        -webkit-transform: rotate(1turn);
        transform: rotate(1turn)
    }
}

.fa-rotate-90 {
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=1)";
    -webkit-transform: rotate(90deg);
    transform: rotate(90deg)
}

.fa-rotate-180 {
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=2)";
    -webkit-transform: rotate(180deg);
    transform: rotate(180deg)
}

.fa-rotate-270 {
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=3)";
    -webkit-transform: rotate(270deg);
    transform: rotate(270deg)
}

.fa-flip-horizontal {
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=0, mirror=1)";
    -webkit-transform: scaleX(-1);
    transform: scaleX(-1)
}

.fa-flip-vertical {
    -webkit-transform: scaleY(-1);
    transform: scaleY(-1)
}

.fa-flip-both, .fa-flip-horizontal.fa-flip-vertical, .fa-flip-vertical {
    -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=2, mirror=1)"
}

.fa-flip-both, .fa-flip-horizontal.fa-flip-vertical {
    -webkit-transform: scale(-1);
    transform: scale(-1)
}

:root .fa-flip-both, :root .fa-flip-horizontal, :root .fa-flip-vertical, :root .fa-rotate-90, :root .fa-rotate-180, :root .fa-rotate-270 {
    -webkit-filter: none;
    filter: none
}

.fa-stack {
    display: inline-block;
    height: 2em;
    line-height: 2em;
    position: relative;
    vertical-align: middle;
    width: 2.5em
}

.fa-stack-1x, .fa-stack-2x {
    left: 0;
    position: absolute;
    text-align: center;
    width: 100%
}

.fa-stack-1x {
    line-height: inherit
}

.fa-stack-2x {
    font-size: 2em
}

.fa-inverse {
    color: #fff
}
`);

css.push(...vars.filter(([ico]) => all_icons.includes(ico)).map(([ico, code]) => `.fa-${ico}:before{content:"\\${code}"}`));

css.push(`.sr-only {
    border: 0;
    clip: rect(0, 0, 0, 0);
    height: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    width: 1px
}

.sr-only-focusable:active, .sr-only-focusable:focus {
    clip: auto;
    height: auto;
    margin: 0;
    overflow: visible;
    position: static;
    width: auto
}

@font-face {
    font-family: "Font Awesome 5 Brands";
    font-style: normal;
    font-weight: 400;
    font-display: block;
    src: url(../webfonts/fa-brands-400.eot);
    src: url(../webfonts/fa-brands-400.eot?#iefix) format("embedded-opentype"), url(../webfonts/fa-brands-400.woff2) format("woff2"), url(../webfonts/fa-brands-400.woff) format("woff"), url(../webfonts/fa-brands-400.ttf) format("truetype"), url(../webfonts/fa-brands-400.svg#fontawesome) format("svg")
}

.fab {
    font-family: "Font Awesome 5 Brands";
    font-weight: 400
}

@font-face {
    font-family: "Font Awesome 5 Duotone";
    font-style: normal;
    font-weight: 900;
    font-display: block;
    src: url(../webfonts/fa-duotone-900.eot);
    src: url(../webfonts/fa-duotone-900.eot?#iefix) format("embedded-opentype"), url(../webfonts/fa-duotone-900.woff2) format("woff2"), url(../webfonts/fa-duotone-900.woff) format("woff"), url(../webfonts/fa-duotone-900.ttf) format("truetype"), url(../webfonts/fa-duotone-900.svg#fontawesome) format("svg")
}

.fad {
    position: relative;
    font-family: "Font Awesome 5 Duotone";
    font-weight: 900
}

.fad:before {
    position: absolute;
    color: var(--fa-primary-color, inherit);
    opacity: 1;
    opacity: var(--fa-primary-opacity, 1)
}

.fad:after {
    color: var(--fa-secondary-color, inherit)
}

.fa-swap-opacity .fad:before, .fad.fa-swap-opacity:before, .fad:after {
    opacity: .4;
    opacity: var(--fa-secondary-opacity, .4)
}

.fa-swap-opacity .fad:after, .fad.fa-swap-opacity:after {
    opacity: 1;
    opacity: var(--fa-primary-opacity, 1)
}

.fad.fa-inverse {
    color: #fff
}

.fad.fa-stack-1x, .fad.fa-stack-2x {
    position: absolute
}

.fad.fa-fw:before, .fad.fa-stack-1x:before, .fad.fa-stack-2x:before {
    left: 50%;
    -webkit-transform: translateX(-50%);
    transform: translateX(-50%)
}
`);

css.push(...vars.filter(([ico]) => sets.duotone.includes(ico)).map(([ico, code]) => `.fad.fa-${ico}:after{content:"\\10${code}"}`));

css.push(`@font-face {
    font-family: "Font Awesome 5 Pro";
    font-style: normal;
    font-weight: 300;
    font-display: block;
    src: url(../webfonts/fa-light-300.eot);
    src: url(../webfonts/fa-light-300.eot?#iefix) format("embedded-opentype"), url(../webfonts/fa-light-300.woff2) format("woff2"), url(../webfonts/fa-light-300.woff) format("woff"), url(../webfonts/fa-light-300.ttf) format("truetype"), url(../webfonts/fa-light-300.svg#fontawesome) format("svg")
}

.fal {
    font-weight: 300
}

@font-face {
    font-family: "Font Awesome 5 Pro";
    font-style: normal;
    font-weight: 400;
    font-display: block;
    src: url(../webfonts/fa-regular-400.eot);
    src: url(../webfonts/fa-regular-400.eot?#iefix) format("embedded-opentype"), url(../webfonts/fa-regular-400.woff2) format("woff2"), url(../webfonts/fa-regular-400.woff) format("woff"), url(../webfonts/fa-regular-400.ttf) format("truetype"), url(../webfonts/fa-regular-400.svg#fontawesome) format("svg")
}

.fal, .far {
    font-family: "Font Awesome 5 Pro"
}

.far {
    font-weight: 400
}

@font-face {
    font-family: "Font Awesome 5 Pro";
    font-style: normal;
    font-weight: 900;
    font-display: block;
    src: url(../webfonts/fa-solid-900.eot);
    src: url(../webfonts/fa-solid-900.eot?#iefix) format("embedded-opentype"), url(../webfonts/fa-solid-900.woff2) format("woff2"), url(../webfonts/fa-solid-900.woff) format("woff"), url(../webfonts/fa-solid-900.ttf) format("truetype"), url(../webfonts/fa-solid-900.svg#fontawesome) format("svg")
}

.fa, .fas {
    font-family: "Font Awesome 5 Pro";
    font-weight: 900
}
`);

const cssStr = css.map(c => c.replaceAll("\n\n", "\n")).join("\n");

[omacranger]

That's cool! I'm not sure an issue on this repo is the right place for it, but I do think it would pair well as a related repo or gist. Ideally it would pull from the SCSS partials and generate that dynamically so you wouldn't have to update it whenever the upstream fontawesome file changes as well.