ERROR: Transforming const to the configured target environment

[eugeniosegala]

Hello,

I'm experiencing an issue after upgrading ESBuild to version 0.18.20.

To be fully transparent, I'm using Vite 4.4.9 (I recently upgraded it by a few minors) and it looks like ESBuild was also upgraded as side-effect (just normal dependencies semver updates).

Every time I run the usual npm run build, I get:

error during build:
Error: Transform failed with 5 errors:
assets/header-!~{008}~.js:5:2: ERROR: Transforming const to the configured target environment ("chrome79", "edge114", "firefox114", "ios12", "safari9.1" + 3 overrides) is not supported yet
assets/header-!~{008}~.js:6:57: ERROR: Transforming const to the configured target environment ("chrome79", "edge114", "firefox114", "ios12", "safari9.1" + 3 overrides) is not supported yet
assets/header-!~{008}~.js:8:4: ERROR: Transforming const to the configured target environment ("chrome79", "edge114", "firefox114", "ios12", "safari9.1" + 3 overrides) is not supported yet
assets/header-!~{008}~.js:786:0: ERROR: Transforming const to the configured target environment ("chrome79", "edge114", "firefox114", "ios12", "safari9.1" + 3 overrides) is not supported yet
assets/header-!~{008}~.js:788:0: ERROR: Transforming const to the configured target environment ("chrome79", "edge114", "firefox114", "ios12", "safari9.1" + 3 overrides) is not supported yet

If I remove the target option from my Vite config file, the issue will disappear.

build: {
   outDir: "build",
   target: ["chrome79", "edge114", "firefox114", "ios12", "safari9.1"],
},

I'm aware that Vite uses ESBuild behind the scenes, and the target property is actually passed to it.

What could be causing the issue?

[hyrious]

Safari9.1 does not support ES6, so it can only use var etc. esbuild does not support lowering newer syntaxes to ES5.

[eugeniosegala]

Hey @hyrious, thank you for your replay.

I think I know where the problem is, the list inside the target is generated using browserslist.

"browserslist": [
    "last 2 versions",
    "not dead",
    "safari >= 12",
    "ios_saf >= 12.1",
    "IE 11",
    "> 0.2%"
  ]

So I'm assuming there was a change in how the above was translated as it went from:

[ "chrome79", "edge111'" "firefox111", "ios12", "safari12" ]

to

[ 'chrome79', 'edge114', 'firefox114', 'ios12', 'safari9.1' ]

I basically reverted browserslist from 4.21.10 to 4.21.3 and the issue disappeared. I think there must a change in how the > 0.2% is calculated.

This issue can be closed as it's not related to ESBuild, I will reach out to the browserslist team, thanks!