restrict-plus-operands

Require both operands of addition to have type number or string.

Attributes

• Included in configs
  • ✅ Recommended
  • 🔒 Strict
• Fixable
  • 🔧 Automated Fixer
  • 💡 Suggestion Fixer
• 💭 Requires type information

Rule Details

Examples of code for this rule:

❌ Incorrect

var foo = '5.5' + 5;
var foo = 1n + 1;

✅ Correct

var foo = parseInt('5.5', 10) + 10;
var foo = 1n + 1n;

.eslintrc.cjs

module.exports = {
  "rules": {
    "@typescript-eslint/restrict-plus-operands": "error"
  }
};

Options

This rule accepts an options object with the following properties:

interface Options {
  /**
   * Whether to check compound assignments such as `+=`.
   */
  checkCompoundAssignments?: boolean;
  /**
   * Whether to allow `any` typed values.
   */
  allowAny?: boolean;
}

const defaultOptions: Options = [
  { checkCompoundAssignments: false, allowAny: false },
];

checkCompoundAssignments

Examples of code for this rule with { checkCompoundAssignments: true }:

❌ Incorrect

/*eslint @typescript-eslint/restrict-plus-operands: ["error", { "checkCompoundAssignments": true }]*/

let foo: string | undefined;
foo += 'some data';

let bar: string = '';
bar += 0;

✅ Correct

/*eslint @typescript-eslint/restrict-plus-operands: ["error", { "checkCompoundAssignments": true }]*/

let foo: number = 0;
foo += 1;

let bar = '';
bar += 'test';

allowAny

Examples of code for this rule with { allowAny: true }:

❌ Incorrect

var fn = (a: any, b: boolean) => a + b;
var fn = (a: any, b: []) => a + b;
var fn = (a: any, b: {}) => a + b;

✅ Correct

var fn = (a: any, b: any) => a + b;
var fn = (a: any, b: string) => a + b;
var fn = (a: any, b: bigint) => a + b;
var fn = (a: any, b: number) => a + b;

How to Use

Resources

• Rule source
• Test source