‘React’ was used before it was defined
From the official documentation. “rules”: { // note you must disable the base rule as it can report incorrect errors “no-use-before-define”: “off”, “@typescript-eslint/no-use-before-define”: [“error”] }
eslint
ESLint: “error Parsing error: The keyword ‘const’ is reserved”
ESLint defaults to ES5 syntax-checking. You’ll want to override to the latest well-supported version of JavaScript. Try adding a .eslintrc.json file to your project. Inside it: { “parserOptions”: { “ecmaVersion”: “latest” }, “env”: { “es6”: true } } Hopefully this helps. EDIT: I also found this example .eslintrc.json which might help.
ESLint Must use destructuring state assignment
That’s called: Enforce consistent usage of destructuring assignment of props, state, and context (react/destructuring-assignment) More details are available here: destructuring-assignment In order to make that warning/error disappear, you could do like this: … const { items }= this.state; … { items.map(item => ( <div key={item}> { item.links.map(thing => ( <NavLink key={thing.link.id} exact to={thing.link.url} > {thing.link.text} … Read more
Unnecessary ‘else’ after ‘return’. (No-else-return)
What that is basically saying is that the else part of the if statement is unnecessary if there is a return in the if part. Something like this is what it expects: if (cctot <= 3 && cctot > 0) { alert(‘Credit under $3.00 not allowed’); return Number.MIN_SAFE_INTEGER; // important to return 0 so we … Read more
Nice way to get rid of no-unused-expressions linter error with chai
You can disable the rule for the entire file using eslint-disable at the top of the file in question: /* eslint-disable no-unused-expressions */ expect(someTrueValue).to.be.true; However, adding this at the top of every test file can be tedious. To disable this rule for all relevant files, you can: Put a new .eslintc configuration file in the … Read more
Disable ESLint that create-react-app provides
As of react-scripts v4.0.2, you can now opt out of ESLint with an environment variable. You can do this by adding it to your .env file, or by prefixing your scripts in your package.json file. For example in .env: DISABLE_ESLINT_PLUGIN=true Or in your package.json: { “scripts”: { “start”: “DISABLE_ESLINT_PLUGIN=true react-scripts start”, “build”: “DISABLE_ESLINT_PLUGIN=true react-scripts build”, … Read more
ESLint dollar($) is not defined. (no-undef)
You are missing “env”: { “browser”: true, “commonjs”: true, “es6”: true, “jquery”: true }, $ is not declared as a global without jquery environment enabled. Because of that, you are getting a no-undef error, saying that you are using variable that haven’t been declared.
JSX not allowed in files with extension ‘ .js’ with eslint-config-airbnb
Either change your file extensions to .jsx as mentioned or disable the jsx-filename-extension rule. You can add the following to your config to allow .js extensions for JSX. “rules”: { “react/jsx-filename-extension”: [1, { “extensions”: [“.js”, “.jsx”] }], }
ESLint – “window” is not defined. How to allow global variables in package.json
There is a builtin environment: browser that includes window. Example .eslintrc.json: “env”: { “browser”: true, “node”: true, “jasmine”: true }, More information: https://eslint.org/docs/user-guide/configuring/language-options#specifying-environments Also see the package.json answer by chevin99 below.