JavaScript – Avoid Use Of Function Constructors

Rule number #

SN-0127

Impact #

In addition to being obtuse from a syntax perspective, function constructors are also dangerous: their execution evaluates the constructor string arguments similar to the way eval works, which could expose your program to random, unintended code which can be both slow and a security risk.

Remediation #

Avoid function constructors altogether.

Time to fix #

30 min

References #

This rule is linked to Common Weakness Enumeration CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code (Eval Injection).

Code examples #

Noncompliant code #

var obj = new Function(“return ” + data)(); // Noncompliant

Compliant code #

var obj = JSON.parse(data);