WebGLRenderingContext: метод attachShader()

attachShader(program, shader)

const program = gl.createProgram();

// Attach pre-existing shaders
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);

gl.linkProgram(program);

if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
  const info = gl.getProgramInfoLog(program);
  throw `Could not compile WebGL program. \n\n${info}`;
}