The WebGLRenderingContext.getShaderPrecisionFormat() method of the WebGL API returns a new WebGLShaderPrecisionFormat object describing the range and precision for the specified shader numeric format.

shaderType

Either a gl.FRAGMENT_SHADER or a gl.VERTEX_SHADER.

precisionType

A precision type value. Either gl.LOW_FLOAT, gl.MEDIUM_FLOAT, gl.HIGH_FLOAT, gl.LOW_INT, gl.MEDIUM_INT, or gl.HIGH_INT.

A WebGLShaderPrecisionFormat object or null, if an error occurs.

• gl.INVALID_ENUM if the shader or precision types aren't recognized.
• gl.INVALID_OPERATION if the shader compiler isn't supported.

The following code gets the precision format of a gl.VERTEX_SHADER with a gl.MEDIUM_FLOAT precision type.

const canvas = document.getElementById("canvas");
const gl = canvas.getContext("webgl");

gl.getShaderPrecisionFormat(gl.VERTEX_SHADER, gl.MEDIUM_FLOAT);
// WebGLShaderPrecisionFormat { rangeMin: 127, rangeMax: 127, precision: 23 }

• WebGLShaderPrecisionFormat