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restrict-plus-operands

When adding two variables, operands must both be of type number or of type string.

Rule Details

Examples of code for this rule:

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

Options

The rule accepts an options object with the following properties:

type Options = {
// if true, check compound assignments (`+=`)
checkCompoundAssignments?: boolean;
// if true, 'any' itself and `string`,`bigint`, `number` is allowed.
allowAny?: boolean;
};

const defaults = {
checkCompoundAssignments: false,
allowAny: false,
};

checkCompoundAssignments

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

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

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

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

allowAny

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

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

How to Use

{
"@typescript-eslint/restrict-plus-operands": "error"
}

Attributes

  • Configs:
    • ✅ Recommended
    • 🔒 Strict
  • 🔧 Fixable
  • 💭 Requires type information