/
prefer-as-const.ts
81 lines (78 loc) · 2.38 KB
/
prefer-as-const.ts
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import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
import { AST_NODE_TYPES } from '@typescript-eslint/utils';
import { createRule } from '../util';
export default createRule({
name: 'prefer-as-const',
meta: {
type: 'suggestion',
docs: {
description: 'Enforce the use of `as const` over literal type',
recommended: 'recommended',
},
fixable: 'code',
hasSuggestions: true,
messages: {
preferConstAssertion:
'Expected a `const` instead of a literal type assertion.',
variableConstAssertion:
'Expected a `const` assertion instead of a literal type annotation.',
variableSuggest: 'You should use `as const` instead of type annotation.',
},
schema: [],
},
defaultOptions: [],
create(context) {
function compareTypes(
valueNode: TSESTree.Expression,
typeNode: TSESTree.TypeNode,
canFix: boolean,
): void {
if (
valueNode.type === AST_NODE_TYPES.Literal &&
typeNode.type === AST_NODE_TYPES.TSLiteralType &&
'raw' in typeNode.literal &&
valueNode.raw === typeNode.literal.raw
) {
if (canFix) {
context.report({
node: typeNode,
messageId: 'preferConstAssertion',
fix: fixer => fixer.replaceText(typeNode, 'const'),
});
} else {
context.report({
node: typeNode,
messageId: 'variableConstAssertion',
suggest: [
{
messageId: 'variableSuggest',
fix: (fixer): TSESLint.RuleFix[] => [
fixer.remove(typeNode.parent),
fixer.insertTextAfter(valueNode, ' as const'),
],
},
],
});
}
}
}
return {
TSAsExpression(node): void {
compareTypes(node.expression, node.typeAnnotation, true);
},
TSTypeAssertion(node): void {
compareTypes(node.expression, node.typeAnnotation, true);
},
PropertyDefinition(node): void {
if (node.value && node.typeAnnotation) {
compareTypes(node.value, node.typeAnnotation.typeAnnotation, false);
}
},
VariableDeclarator(node): void {
if (node.init && node.id.typeAnnotation) {
compareTypes(node.init, node.id.typeAnnotation.typeAnnotation, false);
}
},
};
},
});