ban-date-comparison.ts

import { ESLintUtils, TSESTree } from '@typescript-eslint/utils';
import * as tsutils from 'tsutils';
import * as ts from 'typescript';

export const rule = ESLintUtils.RuleCreator.withoutDocs({
  meta: {
    docs: {
      description: 'ban date comparison using ==, ===, !=, !==',
      recommended: 'warn',
    },
    schema: [],
    messages: {
      unexpected:
        'Use `date.getTime()` instead to compare timestamps using < or >.',
    },
    type: 'problem',
  },
  defaultOptions: [],
  create(context) {
    const { esTreeNodeToTSNodeMap, program } =
      ESLintUtils.getParserServices(context);

    const checker = program.getTypeChecker();

    function isDate(node: TSESTree.Node): boolean {
      const tsNode = esTreeNodeToTSNodeMap.get(node);
      const type = checker.getTypeAtLocation(tsNode);

      return (
        tsutils.isTypeFlagSet(type, ts.TypeFlags.Object) &&
        type.symbol.name === 'Date'
      );
    }

    return {
      BinaryExpression: (node) => {
        if (
          node.operator === '==' ||
          node.operator === '===' ||
          node.operator === '!=' ||
          node.operator === '!=='
        ) {
          if (isDate(node.left) && isDate(node.right)) {
            context.report({
              node,
              messageId: 'unexpected',
            });
          }
        }
      },
    };
  },
});