WebGL index-based name mangling

build.js

const WEBGL_NAMES = ["ACTIVE_ATTRIBUTES","ACTIVE_TEXTURE","ACTIVE_UNIFORMS","ALIASED_LINE_WIDTH_RANGE","ALIASED_POINT_SIZE_RANGE","ALPHA","ALPHA_BITS","ALWAYS","ARRAY_BUFFER","ARRAY_BUFFER_BINDING","ATTACHED_SHADERS","BACK","BLEND","BLEND_COLOR","BLEND_DST_ALPHA","BLEND_DST_RGB","BLEND_EQUATION","BLEND_EQUATION_ALPHA","BLEND_EQUATION_RGB","BLEND_SRC_ALPHA","BLEND_SRC_RGB","BLUE_BITS","BOOL","BOOL_VEC2","BOOL_VEC3","BOOL_VEC4","BROWSER_DEFAULT_WEBGL","BUFFER_SIZE","BUFFER_USAGE","BYTE","CCW","CLAMP_TO_EDGE","COLOR_ATTACHMENT0","COLOR_BUFFER_BIT","COLOR_CLEAR_VALUE","COLOR_WRITEMASK","COMPILE_STATUS","COMPRESSED_TEXTURE_FORMATS","CONSTANT_ALPHA","CONSTANT_COLOR","CONTEXT_LOST_WEBGL","CULL_FACE","CULL_FACE_MODE","CURRENT_PROGRAM","CURRENT_VERTEX_ATTRIB","CW","DECR","DECR_WRAP","DELETE_STATUS","DEPTH_ATTACHMENT","DEPTH_BITS","DEPTH_BUFFER_BIT","DEPTH_CLEAR_VALUE","DEPTH_COMPONENT","DEPTH_COMPONENT16","DEPTH_FUNC","DEPTH_RANGE","DEPTH_STENCIL","DEPTH_STENCIL_ATTACHMENT","DEPTH_TEST","DEPTH_WRITEMASK","DITHER","DONT_CARE","DST_ALPHA","DST_COLOR","DYNAMIC_DRAW","ELEMENT_ARRAY_BUFFER","ELEMENT_ARRAY_BUFFER_BINDING","EQUAL","FASTEST","FLOAT","FLOAT_MAT2","FLOAT_MAT3","FLOAT_MAT4","FLOAT_VEC2","FLOAT_VEC3","FLOAT_VEC4","FRAGMENT_SHADER","FRAMEBUFFER","FRAMEBUFFER_ATTACHMENT_OBJECT_NAME","FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE","FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE","FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL","FRAMEBUFFER_BINDING","FRAMEBUFFER_COMPLETE","FRAMEBUFFER_INCOMPLETE_ATTACHMENT","FRAMEBUFFER_INCOMPLETE_DIMENSIONS","FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT","FRAMEBUFFER_UNSUPPORTED","FRONT","FRONT_AND_BACK","FRONT_FACE","FUNC_ADD","FUNC_REVERSE_SUBTRACT","FUNC_SUBTRACT","GENERATE_MIPMAP_HINT","GEQUAL","GREATER","GREEN_BITS","HIGH_FLOAT","HIGH_INT","IMPLEMENTATION_COLOR_READ_FORMAT","IMPLEMENTATION_COLOR_READ_TYPE","INCR","INCR_WRAP","INT","INT_VEC2","INT_VEC3","INT_VEC4","INVALID_ENUM","INVALID_FRAMEBUFFER_OPERATION","INVALID_OPERATION","INVALID_VALUE","INVERT","KEEP","LEQUAL","LESS","LINEAR","LINEAR_MIPMAP_LINEAR","LINEAR_MIPMAP_NEAREST","LINES","LINE_LOOP","LINE_STRIP","LINE_WIDTH","LINK_STATUS","LOW_FLOAT","LOW_INT","LUMINANCE","LUMINANCE_ALPHA","MAX_COMBINED_TEXTURE_IMAGE_UNITS","MAX_CUBE_MAP_TEXTURE_SIZE","MAX_FRAGMENT_UNIFORM_VECTORS","MAX_RENDERBUFFER_SIZE","MAX_TEXTURE_IMAGE_UNITS","MAX_TEXTURE_SIZE","MAX_VARYING_VECTORS","MAX_VERTEX_ATTRIBS","MAX_VERTEX_TEXTURE_IMAGE_UNITS","MAX_VERTEX_UNIFORM_VECTORS","MAX_VIEWPORT_DIMS","MEDIUM_FLOAT","MEDIUM_INT","MIRRORED_REPEAT","NEAREST","NEAREST_MIPMAP_LINEAR","NEAREST_MIPMAP_NEAREST","NEVER","NICEST","NONE","NOTEQUAL","NO_ERROR","ONE","ONE_MINUS_CONSTANT_ALPHA","ONE_MINUS_CONSTANT_COLOR","ONE_MINUS_DST_ALPHA","ONE_MINUS_DST_COLOR","ONE_MINUS_SRC_ALPHA","ONE_MINUS_SRC_COLOR","OUT_OF_MEMORY","PACK_ALIGNMENT","POINTS","POLYGON_OFFSET_FACTOR","POLYGON_OFFSET_FILL","POLYGON_OFFSET_UNITS","RED_BITS","RENDERBUFFER","RENDERBUFFER_ALPHA_SIZE","RENDERBUFFER_BINDING","RENDERBUFFER_BLUE_SIZE","RENDERBUFFER_DEPTH_SIZE","RENDERBUFFER_GREEN_SIZE","RENDERBUFFER_HEIGHT","RENDERBUFFER_INTERNAL_FORMAT","RENDERBUFFER_RED_SIZE","RENDERBUFFER_STENCIL_SIZE","RENDERBUFFER_WIDTH","RENDERER","REPEAT","REPLACE","RGB","RGB565","RGB5_A1","RGBA","RGBA4","SAMPLER_2D","SAMPLER_CUBE","SAMPLES","SAMPLE_ALPHA_TO_COVERAGE","SAMPLE_BUFFERS","SAMPLE_COVERAGE","SAMPLE_COVERAGE_INVERT","SAMPLE_COVERAGE_VALUE","SCISSOR_BOX","SCISSOR_TEST","SHADER_TYPE","SHADING_LANGUAGE_VERSION","SHORT","SRC_ALPHA","SRC_ALPHA_SATURATE","SRC_COLOR","STATIC_DRAW","STENCIL_ATTACHMENT","STENCIL_BACK_FAIL","STENCIL_BACK_FUNC","STENCIL_BACK_PASS_DEPTH_FAIL","STENCIL_BACK_PASS_DEPTH_PASS","STENCIL_BACK_REF","STENCIL_BACK_VALUE_MASK","STENCIL_BACK_WRITEMASK","STENCIL_BITS","STENCIL_BUFFER_BIT","STENCIL_CLEAR_VALUE","STENCIL_FAIL","STENCIL_FUNC","STENCIL_INDEX8","STENCIL_PASS_DEPTH_FAIL","STENCIL_PASS_DEPTH_PASS","STENCIL_REF","STENCIL_TEST","STENCIL_VALUE_MASK","STENCIL_WRITEMASK","STREAM_DRAW","SUBPIXEL_BITS","TEXTURE","TEXTURE0","TEXTURE1","TEXTURE10","TEXTURE11","TEXTURE12","TEXTURE13","TEXTURE14","TEXTURE15","TEXTURE16","TEXTURE17","TEXTURE18","TEXTURE19","TEXTURE2","TEXTURE20","TEXTURE21","TEXTURE22","TEXTURE23","TEXTURE24","TEXTURE25","TEXTURE26","TEXTURE27","TEXTURE28","TEXTURE29","TEXTURE3","TEXTURE30","TEXTURE31","TEXTURE4","TEXTURE5","TEXTURE6","TEXTURE7","TEXTURE8","TEXTURE9","TEXTURE_2D","TEXTURE_BINDING_2D","TEXTURE_BINDING_CUBE_MAP","TEXTURE_CUBE_MAP","TEXTURE_CUBE_MAP_NEGATIVE_X","TEXTURE_CUBE_MAP_NEGATIVE_Y","TEXTURE_CUBE_MAP_NEGATIVE_Z","TEXTURE_CUBE_MAP_POSITIVE_X","TEXTURE_CUBE_MAP_POSITIVE_Y","TEXTURE_CUBE_MAP_POSITIVE_Z","TEXTURE_MAG_FILTER","TEXTURE_MIN_FILTER","TEXTURE_WRAP_S","TEXTURE_WRAP_T","TRIANGLES","TRIANGLE_FAN","TRIANGLE_STRIP","UNPACK_ALIGNMENT","UNPACK_COLORSPACE_CONVERSION_WEBGL","UNPACK_FLIP_Y_WEBGL","UNPACK_PREMULTIPLY_ALPHA_WEBGL","UNSIGNED_BYTE","UNSIGNED_INT","UNSIGNED_SHORT","UNSIGNED_SHORT_4_4_4_4","UNSIGNED_SHORT_5_5_5_1","UNSIGNED_SHORT_5_6_5","VALIDATE_STATUS","VENDOR","VERSION","VERTEX_ATTRIB_ARRAY_BUFFER_BINDING","VERTEX_ATTRIB_ARRAY_ENABLED","VERTEX_ATTRIB_ARRAY_NORMALIZED","VERTEX_ATTRIB_ARRAY_POINTER","VERTEX_ATTRIB_ARRAY_SIZE","VERTEX_ATTRIB_ARRAY_STRIDE","VERTEX_ATTRIB_ARRAY_TYPE","VERTEX_SHADER","VIEWPORT","ZERO","activeTexture","attachShader","bindAttribLocation","bindBuffer","bindFramebuffer","bindRenderbuffer","bindTexture","blendColor","blendEquation","blendEquationSeparate","blendFunc","blendFuncSeparate","bufferData","bufferSubData","canvas","checkFramebufferStatus","clear","clearColor","clearDepth","clearStencil","colorMask","compileShader","compressedTexImage2D","compressedTexSubImage2D","copyTexImage2D","copyTexSubImage2D","createBuffer","createFramebuffer","createProgram","createRenderbuffer","createShader","createTexture","cullFace","deleteBuffer","deleteFramebuffer","deleteProgram","deleteRenderbuffer","deleteShader","deleteTexture","depthFunc","depthMask","depthRange","detachShader","disable","disableVertexAttribArray","drawArrays","drawElements","drawingBufferHeight","drawingBufferWidth","enable","enableVertexAttribArray","finish","flush","framebufferRenderbuffer","framebufferTexture2D","frontFace","generateMipmap","getActiveAttrib","getActiveUniform","getAttachedShaders","getAttribLocation","getBufferParameter","getContextAttributes","getError","getExtension","getFramebufferAttachmentParameter","getParameter","getProgramInfoLog","getProgramParameter","getRenderbufferParameter","getShaderInfoLog","getShaderParameter","getShaderPrecisionFormat","getShaderSource","getSupportedExtensions","getTexParameter","getUniform","getUniformLocation","getVertexAttrib","getVertexAttribOffset","hint","isBuffer","isContextLost","isEnabled","isFramebuffer","isProgram","isRenderbuffer","isShader","isTexture","lineWidth","linkProgram","pixelStorei","polygonOffset","readPixels","renderbufferStorage","sampleCoverage","scissor","shaderSource","stencilFunc","stencilFuncSeparate","stencilMask","stencilMaskSeparate","stencilOp","stencilOpSeparate","texImage2D","texParameterf","texParameteri","texSubImage2D","uniform1f","uniform1fv","uniform1i","uniform1iv","uniform2f","uniform2fv","uniform2i","uniform2iv","uniform3f","uniform3fv","uniform3i","uniform3iv","uniform4f","uniform4fv","uniform4i","uniform4iv","uniformMatrix2fv","uniformMatrix3fv","uniformMatrix4fv","useProgram","validateProgram","vertexAttrib1f","vertexAttrib1fv","vertexAttrib2f","vertexAttrib2fv","vertexAttrib3f","vertexAttrib3fv","vertexAttrib4f","vertexAttrib4fv","vertexAttribPointer","viewport"];

// As part of the build process, run your source code throught this function:
const replaceGLRefs = code => {
    WEBGL_NAMES.forEach(name => {
        code = code.replace(
            new RegExp(`gl\\.${name}([^a-zA-Z0-9])`, 'g'),
            `gl[${ WEBGL_NAMES.indexOf(name) }]$1`
        );
    });

    return code;
};

target.js

let gl = canvas.getContext('webgl');

// Place this right after gl is first declared.
// STENCIL_INDEX and releaseShaderCompiler are present only in Safari, so we need
// to filter them out to get consistent indices across browsers.
let f = [], k;
for(k in gl)k!='STENCIL_INDEX'&&k!='releaseShaderCompiler'&&f.push(k);
for(k in gl)gl[f.sort().indexOf(k)]=gl[k];