Dead variables should not be used

• UNUSED_VAR_ASSIGN
• Code Quality
• Low
• cwe

This rule applies when a variable is assigned a value that is not used by subsequent code or is overwritten by another assignment without use.

The value is dead so that it might imply a mistake or unnecessary code.

Note:

1. Not applied when the variable name starts with _ because we regard it as intentionally unused.
2. Not applied for the assignment with initialization values like "", '', 0, true, !0, false, !1, null, undefined, void …, {}, [].
3. Not applied for the assignment saving this context because it is often used as boilerplate (e.g. let self = this;).
4. Not applied at test case code because unused values are usually harmless at tests and tend to occur more. Currently, BDD, TDD and QUnit style test cases are recognized.

Noncompliant Code Example

function foo(url) {
    var target = url + "user" + user; // UNUSED_VAR_ASSIGN alarm
    target = url.replace(/\.|\?|\&|\/|\=|\:|\-|\s/gi, ""); // UNUSED_VAR_ASSIGN alarm
}

Compliant Code Example

function foo(url) {
    var target = url + "user" + user;
    target = target.replace(/\.|\?|\&|\/|\=|\:|\-|\s/gi, "");
    return target;
}

Version

This rule was introduced in DeepScan 1.0.0-alpha.

See

• CWE-563

• MISRA C:2012, Rule 2.2: There shall be no dead code