Major bug-risk Should not have unused variables

[philipjonsen]

D is defined but never used here https://github.com/philipjonsen/tenderly-fork/blob/master/create.js#L70-L70

Having unused variables are dangerous to injections and such.

Unused variables are most often the result of incomplete refactoring. They can lead to confusing code and minor performance hitches.

Easy Fix:

Bad Practice

// Write-only variables are not considered as used.
let y = 10;
y = 5;

// A variable that modifies only itself isn't considered used.
let z = 0;
z = z + 1;

// Unused argument
(function(x) {
return 5;
})();

// Unused recursive functions also raise this issue.
function fact(n) {
if (n < 2) return 1;
return n * fact(n - 1);
}

// When a function definition destructures an array,
// unused entries from the array also cause warnings.
function getY([x, y]) {
return y;
}

Recommended

let x = 10;
alert(x);

((arg1) => {
return arg1;
})();

let myFunc;
myFunc = (n) => {
// this is legal
if (n < 0) myFunc();
};

// this is also considered legal
console.log(declaredLater);
var declaredLater;

// Only the second argument from the descructured array is used.
function getY([, y]) {
return y;
}