ref: 3b2fe3cd33b74166c3debec9826826f2b5a54fd9
parent: 85e4dd7370eae97ae367e596aa6a10ba42fd4b7c
author: Bjørn Erik Pedersen <bjorn.erik.pedersen@gmail.com>
date: Tue Nov 3 04:05:09 EST 2020
js: Add avoidTDZ option Fixes #7865
--- a/docs/content/en/hugo-pipes/js.md
+++ b/docs/content/en/hugo-pipes/js.md
@@ -40,6 +40,9 @@
minify [bool]
: Let `js.Build` handle the minification.
+avoidTDZ {{< new-in "0.78.0" >}}+: There is/was a bug in WebKit with severe performance issue with the tracking of TDZ checks in JavaScriptCore. Enabling this flag removes the TDZ and `const` assignment checks and may improve performance of larger JS codebases until the WebKit fix is in widespread use. See https://bugs.webkit.org/show_bug.cgi?id=199866
+
target [string]
: The language target.
One of: `es5`, `es2015`, `es2016`, `es2017`, `es2018`, `es2019`, `es2020` or `esnext`.
--- a/go.sum
+++ b/go.sum
@@ -459,6 +459,8 @@
github.com/spf13/afero v1.2.2/go.mod h1:9ZxEEn6pIJ8Rxe320qSDBk6AsU0r9pR7Q4OcevTdifk=
github.com/spf13/afero v1.4.0 h1:jsLTaI1zwYO3vjrzHalkVcIHXTNmdQFepW4OI8H3+x8=
github.com/spf13/afero v1.4.0/go.mod h1:Ai8FlHk4v/PARR026UzYexafAt9roJ7LcLMAmO6Z93I=
+github.com/spf13/afero v1.4.1 h1:asw9sl74539yqavKaglDM5hFpdJVK0Y5Dr/JOgQ89nQ=
+github.com/spf13/afero v1.4.1/go.mod h1:Ai8FlHk4v/PARR026UzYexafAt9roJ7LcLMAmO6Z93I=
github.com/spf13/cast v1.3.0 h1:oget//CVOEoFewqQxwr0Ej5yjygnqGkvggSE/gB35Q8=
github.com/spf13/cast v1.3.0/go.mod h1:Qx5cxh0v+4UWYiBimWS+eyWzqEqokIECu5etghLkUJE=
github.com/spf13/cast v1.3.1 h1:nFm6S0SMdyzrzcmThSipiEubIDy8WEXKNZ0UOgiRpng=
--- a/resources/resource_transformers/js/options.go
+++ b/resources/resource_transformers/js/options.go
@@ -70,6 +70,16 @@
// What to use instead of React.Fragment.
JSXFragment string
+ // There is/was a bug in WebKit with severe performance issue with the tracking
+ // of TDZ checks in JavaScriptCore.
+ //
+ // Enabling this flag removes the TDZ and `const` assignment checks and
+ // may improve performance of larger JS codebases until the WebKit fix
+ // is in widespread use.
+ //
+ // See https://bugs.webkit.org/show_bug.cgi?id=199866
+ AvoidTDZ bool
+
mediaType media.Type
outDir string
contents string
@@ -338,6 +348,8 @@
JSXFactory: opts.JSXFactory,
JSXFragment: opts.JSXFragment,
+
+ AvoidTDZ: opts.AvoidTDZ,
Tsconfig: opts.tsConfig,
--- a/resources/resource_transformers/js/options_test.go
+++ b/resources/resource_transformers/js/options_test.go
@@ -54,7 +54,12 @@
})
opts, err = toBuildOptions(Options{- Target: "es2018", Format: "cjs", Minify: true, mediaType: media.JavascriptType})
+ Target: "es2018",
+ Format: "cjs",
+ Minify: true,
+ mediaType: media.JavascriptType,
+ AvoidTDZ: true,
+ })
c.Assert(err, qt.IsNil)
c.Assert(opts, qt.DeepEquals, api.BuildOptions{Bundle: true,
@@ -63,6 +68,7 @@
MinifyIdentifiers: true,
MinifySyntax: true,
MinifyWhitespace: true,
+ AvoidTDZ: true,
Stdin: &api.StdinOptions{Loader: api.LoaderJS,
},