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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%.equal() method returns a selection mask with values depending on a strict equality comparison (a === b) in each lane.


SIMD.Float32x4.equal(a, b)
SIMD.Float64x2.equal(a, b)

SIMD.Int8x16.equal(a, b)
SIMD.Int16x8.equal(a, b)
SIMD.Int32x4.equal(a, b)

SIMD.Uint8x16.equal(a, b)
SIMD.Uint16x8.equal(a, b) 
SIMD.Uint32x4.equal(a, b)


An instance of a SIMD type.
Another instance of a SIMD type.

Return value

A selection mask (of type Bool64x2, Bool32x4, Bool16x8 or Bool8x16 depending on the size). The lane values of the mask are either true or false depending on the result of a === b.


The SIMD.%type%.equal method is one of the SIMD comparison operations and does not give you back the values of the equality comparison of two instances directly. Instead, a selection mask with Boolean values is returned.


Selecting equal lanes from two vectors

In this example, two SIMD Float32x4 data types are compared against equality of their lane values and a selection mask gets created based on the result. This selection mask is then used to select the equal values into a new Float32x4. At the lane positions where the vectors a and b have no equal values, the result vector uses the zero vector and fills the lanes with 0.

var a = SIMD.Float32x4(1, 2, 3, 9);
var b = SIMD.Float32x4(1, 4, 7, 9);

var mask = SIMD.Float32x4.equal(a,b);
// Bool32x4[true, false, false, true]

var zero = SIMD.Float32x4(0, 0, 0, 0);

var result = SIMD.Float32x4.select(mask, a, zero);
// Float32x4[1, 0, 0, 9]


Specification Status Comment
The definition of 'SIMDConstructor.equal' 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, rbgo
Last updated by: fscholz,