Example illustrating options for coloring GFF and GTF annotation tracks

1. color by attribute (column 9)
2. color by source (column 2)
3. color by source with color table
4. color by strand

        var options =
        {
            genome: "hg38",
            locus: "chr22:21,913,513-22,216,565",
            tracks:
                [
                    {
                        name: "Color by attribute \"biotype\"",
                        format: "gff3",
                        displayMode: "expanded",
                        height: 300,
                        url: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz",
                        indexURL: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz.tbi",
                        visibilityWindow: 1000000,
                        colorBy: "biotype",
                        // Uncomment to explicitly set a colorTable
                        colorTable: {
                            "antisense": "blueviolet",
                            "protein_coding": "blue",
                            "retained_intron": "rgb(0, 150, 150)",
                            "processed_transcript": "purple",
                            "processed_pseudogene": "#7fff00",
                            "unprocessed_pseudogene": "#d2691e",
                            "*": "black"
                        }
                    },
                    {
                        name: "Color by function",
                        format: "gff3",
                        displayMode: "expanded",
                        height: 300,
                        url: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz",
                        indexURL: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz.tbi",
                        visibilityWindow: 1000000,
                        color: (feature) => {
                            switch (feature.getAttributeValue("biotype")) {
                                case "antisense":
                                    return "blueviolet"
                                case "protein_coding":
                                    return "blue"
                                case "retained_intron":
                                    return "rgb(0, 150, 150)"
                                case "processed_transcript":
                                    return "purple"
                                case "processed_pseudogene":
                                    return "#7fff00"
                                case "unprocessed_pseudogene":
                                    return "#d2691e"
                                default:
                                    return "black"
                            }
                        }
                    },

                    {
                        name: "Color by \"source\"",
                        format: "gff3",
                        displayMode: "expanded",
                        height: 300,
                        url: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz",
                        indexURL: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz.tbi",
                        visibilityWindow: 1000000,
                        colorBy: "source",
                        colorTable: {
                            "Ensembl": "blueviolet",
                            "ensembl": "blueviolet",
                            "ensembl_havana": "purple",
                            "havana": "blue",
                            "insdc": "#7fff00",
                            "mirbase": "#d2691e",
                            "*": "black"
                        }
                    },
                    {
                        name: "Color by \"source\" - default color table",
                        format: "gff3",
                        displayMode: "expanded",
                        height: 300,
                        url: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz",
                        indexURL: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz.tbi",
                        visibilityWindow: 1000000,
                        colorBy: "source",
                    },
                    {
                        name: "Color by strand",
                        format: "gff3",
                        displayMode: "expanded",
                        height: 300,
                        url: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz",
                        indexURL: "https://s3.amazonaws.com/igv.org.genomes/hg38/Homo_sapiens.GRCh38.94.chr.gff3.gz.tbi",
                        visibilityWindow: 1000000,
                        color: "blue",
                        altColor: "red"
                    }
                ]
        }