Recommendation¶

If the two declarations are duplicates, remove one of them. Otherwise, rename one of them to distinguish the two functions, or turn the function declarations into assignments of function expressions to the same local variable.

Example¶

In the following example, function converter is defined differently in the two branches of the if statement. However, the function definition appearing later in the program text will override the one appearing earlier, independent of the flow of execution through the if statement, so in this case it is always the second function that is returned. (Note that this may not be true on older browsers.)

function getConverter(dir) {
	if (dir === 'c2f') {
		function converter(c) {
			return c * 9/5 + 32;
		}
	} else {
		function converter(f) {
			return (f - 32) * 5/9;
		}
	}
	return converter;
}

To address this problem, introduce a local variable converter and convert the function declarations into assignments of function expressions to this variable:

function getConverter(dir) {
	var converter;
	if (dir === 'c2f') {
		converter = function (c) {
			return c * 9/5 + 32;
		};
	} else {
		converter = function (f) {
			return (f - 32) * 5/9;
		};
	}
	return converter;
}

References¶

• Ecma International, ECMAScript Language Definition, 5.1 Edition, Section 10.5. ECMA, 2011.

• Common Weakness Enumeration: CWE-563.