Extract glyphs from a font and build a icon-font with gulp

Gulp.js

var opentype = require( 'opentype.js' );
var fs = require( 'fs' );
var _ = require( 'lodash' );

gulp.task( 'icons', function() {
	var icons = [];
	var scss = '[class^="my-icon-"], [class*=" my-icon-"] { display: inline-block; font: normal normal normal 14px/1 "mylaps-icons"; font-size: inherit; text-rendering: auto; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }';

	opentype.load( manifest.dependencies.icons.font[ 0 ], function( err, font ) {
		if ( err ) {
			alert( 'Could not load font: ' + err );
		} else {
			var cache = [];
			var fontfile = JSON.stringify( font, function( key, value ) {
				if ( typeof value === 'object' && value !== null ) {
					if ( cache.indexOf( value ) !== -1 ) {
						return;
					}
					cache.push( value );
				}
				return value;
			} );
			cache = null;

			font_json = JSON.parse( fontfile );

			_.each( font_json.glyphs.glyphs, function( val, key ) {
				if ( val.unicode ) {
					val.cssClass = 'my-icon-' + convertToSlug( val.name );
					val.unicode = formatUnicode( val.unicode );
					icons.push( val );

					var string = '.' + val.cssClass + ' { &::before {content: "\\' + val.unicode + '"; } }\n';
					scss = scss + string;
				}
			} );

			fs.writeFile( manifest.dependencies.icons.json[ 0 ], JSON.stringify( icons ), function( err ) {
				if ( err ) {
					return console.log( err );
				}

				console.log( manifest.dependencies.icons.json + " was saved!" );
			} );

			fs.writeFile( manifest.dependencies.icons.scss[ 0 ], scss, function( err ) {
				if ( err ) {
					return console.log( err );
				}

				console.log( manifest.dependencies.icons.scss + " was saved!" );
			} );

		}
	} );

	function convertToSlug( Text ) {
		return Text
			.toLowerCase()
			.replace( '-', '' )
			.replace( / /g, '-' )
			.replace( /[^\w-]+/g, '' )
			.replace( '--', '-' );
	}


	function formatUnicode( unicode ) {
		unicode = unicode.toString( 16 );
		if ( unicode.length > 4 ) {
			return ( "000000" + unicode.toUpperCase() ).substr( -6 );
		} else {
			return ( "0000" + unicode.toUpperCase() ).substr( -4 );
		}
	}

} );