Found unused expressions JS-0093
Bug risk
Minor
15 days ago
—
3 years old
Found unused expression
90 });
91
92 setTimeout(() => {
93 Registry.currentGrid.spacing; 94 // Associate an onchange function
95 this.$refs.gridslider.noUiSlider.on("change", (params) => {
96 let spacing = parseFloat(params[0]);
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