Found unused expressions in TypeScript code JS-0354
Bug risk
Major
4 months ago
—
3 years old
Expected an assignment or function call and instead saw an expression
1import { exec, exit } from "shelljs";
2
3exec("wintersmith build -X") || exit(1); 4
5exec(
6 "uglifyjs build/app.js" +
Description
An unused expression that does not affect the state of the program indicates a logic error.
For example, if a programmer wants to increment the value of a variable a by one, and intends to do so through this code:
let a = 0
a = a + 1
console.log(a) // output 1
But because of a typo, writes the following:
let a = 0
a + 1
console.log(a)
Here, the expression a + 1 does nothing meaningful in the program's runtime.
The expression is thus considered "unused" and should be removed.
Bad Practice
0
if(0) 0
{0}
f(0), {}
a, b()
c = a, b;
a() && function namedFunctionInExpressionContext () {f();}
(function anIncompleteIIFE () {});
injectGlobal`body{ color: red; }`
Recommended
{} // In this context, this is a block statement, not an object literal
{myLabel: someVar} // In this context, this is a block statement with a label and expression, not an object literal
function namedFunctionDeclaration () {}
(function aGenuineIIFE () {}());
f()
a = 0
new C
delete a.b
void a