The WebGLRenderingContext.bufferSubData() method of the WebGL API updates a subset of a buffer object's data store.


// WebGL1: 
void gl.bufferSubData(target, offset, ArrayBuffer srcData); 
void gl.bufferSubData(target, offset, ArrayBufferView srcData); 

// WebGL2: 
void gl.bufferSubData(target, dstByteOffset, ArrayBufferView srcData, srcOffset, length);


A GLenum specifying the binding point (target). Possible values:
  • gl.ARRAY_BUFFER: Buffer containing vertex attributes, such as vertex coordinates, texture coordinate data, or vertex color data.
  • gl.ELEMENT_ARRAY_BUFFER: Buffer used for element indices.
  • When using a WebGL 2 context, the following values are available additionally:
    • gl.COPY_READ_BUFFER: Buffer for copying from one buffer object to another.
    • gl.COPY_WRITE_BUFFER: Buffer for copying from one buffer object to another.
    • gl.TRANSFORM_FEEDBACK_BUFFER: Buffer for transform feedback operations.
    • gl.UNIFORM_BUFFER: Buffer used for storing uniform blocks.
    • gl.PIXEL_PACK_BUFFER: Buffer used for pixel transfer operations.
    • gl.PIXEL_UNPACK_BUFFER: Buffer used for pixel transfer operations.
A GLintptr specifying an offset in bytes where the data replacement will start.
srcData Optional
An ArrayBufferSharedArrayBuffer or one of the ArrayBufferView typed array types that will be copied into the data store.
A GLuint specifying the element index offset where to start reading the buffer.
length Optional
A GLuint defaulting to 0.

Return value



  • A gl.INVALID_VALUE error is thrown if the data would be written past the end of the buffer or if data is null.
  • A gl.INVALID_ENUM error is thrown if target is not one of the allowed enums.


Using bufferSubData

var canvas = document.getElementById('canvas');
var gl = canvas.getContext('webgl');
var buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, 1024, gl.STATIC_DRAW);
gl.bufferSubData(gl.ARRAY_BUFFER, 512, data);


Specification Status Comment
WebGL 1.0
The definition of 'bufferSubData' in that specification.
Recommendation Initial definition for WebGL.
OpenGL ES 2.0
The definition of 'glBufferSubData' in that specification.
Standard Man page of the OpenGL ES 2 API.
OpenGL ES 3.0
The definition of 'glBufferSubData' in that specification.
Standard Man page of the (similar) OpenGL ES 3 API.

Adds new target buffers:

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support912411125.1
WebGL256 No51 No43 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes25 Yes Yes128.1 Yes
WebGL25858 No5143 No7.0

See also

Document Tags and Contributors

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