JavaScript has special identifiers that, while not reserved, still should not be used as identifiers. They include:

These words should not be bound or assigned, because doing so would overwrite the original definitions of these identifiers. What's more, assigning or binding some of these names will generate an error in JavaScript strict mode code.

Noncompliant Code Example

eval = 17; // Noncompliant
arguments++; // Noncompliant
++eval; // Noncompliant
var obj = { set p(arguments) { } }; // Noncompliant
var eval; // Noncompliant
try { } catch (arguments) { } // Noncompliant
function x(eval) { } // Noncompliant
function arguments() { } // Noncompliant
var y = function eval() { }; // Noncompliant
var f = new Function("arguments", "return 17;"); // Noncompliant

function fun() {
  if (arguments.length == 0) { // Compliant
    // do something
  }
}

Compliant Solution

result = 17;
args++;
++result;
var obj = { set p(arg) { } };
var result;
try { } catch (args) { }
function x(arg) { }
function args() { }
var y = function fun() { };
var f = new Function("args", "return 17;");

function fun() {
  if (arguments.length == 0) {
    // do something
  }
}