SIMD.js has been taken out of active development in TC39 and removed from Stage 3. It is not being pursued by web browsers for implementation anymore. SIMD operations exposed to the web are under active development within WebAssembly, with operations based on the SIMD.js operations.

The static SIMD.%type%.replaceLane() method returns a new SIMD data type with the given lane value replaced.


SIMD.Float32x4.replaceLane(t, index, value)
SIMD.Float64x2.replaceLane(t, index, value)

SIMD.Int8x16.replaceLane(t, index, value)
SIMD.Int16x8.replaceLane(t, index, value)
SIMD.Int32x4.replaceLane(t, index, value)

SIMD.Uint8x16.replaceLane(t, index, value)
SIMD.Uint16x8.replaceLane(t, index, value)
SIMD.Uint32x4.replaceLane(t, index, value)

SIMD.Bool8x16.replaceLane(t, index, value)
SIMD.Bool16x8.replaceLane(t, index, value)
SIMD.Bool32x4.replaceLane(t, index, value)
SIMD.Bool64x2.replaceLane(t, index, value)


An instance of a corresponding SIMD type.
An index number for which lane to replace.
A new value to be used for the lane.

Return value

A new SIMD data type with the given lane value replaced.


  • A TypeError, if t is not the corresponding SIMD type.
  • A RangeError, if the lane index is out of bounds.


var t = SIMD.Float32x4(1, 2, 3, 4);
SIMD.Float32x4.replaceLane(t, 2, 42); 
// Float32x4[1, 2, 42, 4]


Specification Status Comment
The definition of 'SIMDConstructor.replaceLane' in that specification.
Obsolete Initial definition.

Browser compatibility

Experimental SIMD.js has been removed from browsers. It's still available in Firefox Nightly, but will be removed in favor of a SIMD implementation in WebAssembly. See also bug 1416723.

See also

Document Tags and Contributors

 Contributors to this page: fscholz
 Last updated by: fscholz,