The WEBGL_compressed_texture_s3tc extension is part of the WebGL API and exposes four S3TC compressed texture formats.

interface WEBGL_compressed_texture_s3tc {
    COMPRESSED_RGBA_S3TC_DXT1_EXT: number;
    COMPRESSED_RGBA_S3TC_DXT3_EXT: number;
    COMPRESSED_RGBA_S3TC_DXT5_EXT: number;
    COMPRESSED_RGB_S3TC_DXT1_EXT: number;
}

Properties

COMPRESSED_RGBA_S3TC_DXT1_EXT: number
COMPRESSED_RGBA_S3TC_DXT3_EXT: number
COMPRESSED_RGBA_S3TC_DXT5_EXT: number
COMPRESSED_RGB_S3TC_DXT1_EXT: number