ts-r
  • Error
  • Reported by the type checker

TS2357

The operand of an increment or decrement operator must be a variable or a property access.

`++` or `--` is applied to something that isn't a variable or property, such as a call or a literal. Assign to a variable instead.

What it means

Increment and decrement change their operand, so the operand must be something that can be assigned to: a variable, a property or an element access.

Example

index.ts
function count(): number {
  return 1;
}

count()++;
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(5,1): error TS2357: The operand of an increment or decrement operator must be a variable or a property access.

Recorded by node scripts/verify-examples.mjs with ts-r built from commit 6deaf01. The example uses the default tsconfig: strict, target: es2022, module: esnext, moduleResolution: bundler.

How to fix

  • Store the value in a variable and increment that.