Literal Called As Function

ID

javascript.literal_called_as_function

Severity

critical

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

JavaScript

Tags

reliability, runtime-error

Description

Reports a call whose callee is a literal — a string, a number, a boolean, null, or a regular expression — optionally wrapped in parentheses. A literal is never callable, so the line throws a TypeError the first time it runs.

const value = "abc"();     // FLAW — TypeError: "abc" is not a function
const value = (42)();      // FLAW
const value = null();      // FLAW

The callee is read through the parentheses that may wrap it, and only a callee that directly holds a literal counts. A property or method of a literal ("abc".repeat(2)) is callable and ordinary, and the comma-sequence idiom (0, obj.fn)() calls its second operand rather than the literal, so neither is reported.

Rationale

  • The shape comes from an editing slip rather than a misunderstanding, which is why it survives to commit: a call’s parentheses left behind after the callee was replaced by a value, a missing operator between a number and a parenthesised group (const area = 2(w + h)), or a semicolon dropped at the end of a line so a literal and the parenthesised expression under it merged into one call.

  • Nothing about the line looks wrong at a glance — it reads as a call — and the error only surfaces when that path is exercised.

Remediation

Restore the operator or the callee the line was meant to have.

const area = 2 * (w + h);
const value = format(input);
const value = "abc".repeat(2);

References

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