the syntax requires an imported helper named __spreadArrays
JavascriptTypescriptVisual Studio-CodeSpreadJavascript Problem Overview
When I'm trying to use spreading in typescript like:
.reduce((unique, x) => {
unique.some(element => element.machineName === x.machineName) ? unique : [...unique, x];
}
I get warning with red marking from Visual Studio Code:
the syntax requires an imported helper named __spreadArrays
typescript version: "2.3.4"
target: "es5"
I think in later versions this issue is fixed, but right now I can't migrate. How can I fix it?
Note: Project gets compiled fine and works. But red underlying in VS Code in annoying.
Javascript Solutions
Solution 1 - Javascript
In my case the problem it was target: "es5" in compilerOptions at tsconfig.json.
So I change it to es6 to get it works without adding dependency.
Solution 2 - Javascript
Quick fix, short answer
npm install tslib@latest --save
Update
I got this issue again (now with tslib version 2.2.0) after updating VS Code, again updating fixed the issue.
Original
I had this issue with tslib version 1.14.1
npm update tslib --save didn't really do anything
npm install tslib@latest --save did the job, it updated to version 2.2.0
Solution 3 - Javascript
For VS Code the notification is based on the tsLib exports.
Actually nothing bad happens without doing anything, it is just lack of typing.
Solution: Update tsLib dependency to get rid of the highlighting. In my case it was version 1.9.0. Update to 1.10.0 solved the issue.
__spreadArrays is added in 1.10.0 tsLib version:
https://github.com/microsoft/tslib/blob/1.10.0/tslib.es6.js
Update: Since some time passed, it is better to update version to 2.2.0 (based on last comments) or the latest.
Solution 4 - Javascript
Assuming your tslib is installed correctly and up to date, you might still get this error in VS Code if the editor is using a different Typescript version.
(taken from zok's answer on this SO question)
Open Command Palette (Cmd+Shift+P on Mac. Focused file must be .ts or .tsx otherwise it won't show the option to change version) Select "TypeScript: Select TypeScript Version..." It shows VSCode's TS version and Workspace's (project) one, pick the workspace one
Solution 5 - Javascript
This error might happen if you have in your tsconfig.json file :
{
"importHelpers": true,
"target": "es5"
}
If for any reason you can't upgrade to es6, setting importHelpers to false will make the error go away ...
Solution 6 - Javascript
for yarn users: yarn upgrade tslib@latest
Solution 7 - Javascript
from right side down hover on curly braces beside of TypeScript and then click on version it will give you few options, generally related to project just select version and it will work fine
Solution 8 - Javascript
you may need to upgrade to [email protected]
Solution 9 - Javascript
Just make sure tslint is enabled in the bottom of vscode editor options
Solution 10 - Javascript
Ran into this issue with a dependency and resolved it by updating its tsconfig.ts with the path to the top level lastest tslib.
"importHelpers": true,
"paths": {
"tslib": [ "../tslib/tslib.d.ts" ]
}