WebAssembly¶
Go 1.11 Release Notes¶
Go 1.11 adds an experimental port to WebAssembly (js/wasm).
Go programs currently compile to one WebAssembly module that includes the Go runtime for goroutine scheduling, garbage collection, maps, etc. As a result, the resulting size is at minimum around 2 MB, or 500 KB compressed. Go programs can call into JavaScript using the new experimental syscall/js package. Binary size and interop with other languages has not yet been a priority but may be addressed in future releases.
As a result of the addition of the new GOOS value "js" and GOARCH value "wasm", Go files named *_js.go or *_wasm.go will now be ignored by Go tools except when those GOOS/GOARCH values are being used. If you have existing filenames matching those patterns, you will need to rename them.
More information can be found on the WebAssembly wiki page.
Go 1.12 Release Notes¶
The Callback type and NewCallback function have been renamed; they are now called Func and FuncOf, respectively. This is a breaking change, but WebAssembly support is still experimental and not yet subject to the Go 1 compatibility promise. Any code using the old names will need to be updated.
If a type implements the new Wrapper interface, ValueOf will use it to return the JavaScript value for that type.
The meaning of the zero Value has changed. It now represents the JavaScript undefined value instead of the number zero. This is a breaking change, but WebAssembly support is still experimental and not yet subject to the Go 1 compatibility promise. Any code relying on the zero Value to mean the number zero will need to be updated.
The new Value.Truthy method reports the JavaScript "truthiness" of a given value.
Go 1.13 Release Notes¶
For GOARCH=wasm, the new environment variable GOWASM takes a comma-separated list of experimental features that the binary gets compiled with. The valid values are documented here.
Go 1.14 Release Notes¶
JavaScript values referenced from Go via js.Value objects can now be garbage collected.
js.Value values can no longer be compared using the == operator, and instead must be compared using their Equal method.
js.Value now has IsUndefined, IsNull, and IsNaN methods.
Go 1.18 Release Notes¶
On WebAssembly targets, the Dial, DialContext, DialTLS and DialTLSContext method fields in Transport will now be correctly used, if specified, for making HTTP requests.