AvoidWithStatement
Since: PMD 5.0.1
Priority: High (1)
Avoid using with - it’s bad news
This rule is defined by the following XPath expression:
//WithStatement
Example(s):
with (object) {
property = 3; // Might be on object, might be on window: who knows.
}
Use this rule by referencing it:
<rule ref="category/ecmascript/bestpractices.xml/AvoidWithStatement" />
ConsistentReturn
Since: PMD 5.0
Priority: Medium High (2)
ECMAScript does provide for return types on functions, and therefore there is no solid rule as to their usage. However, when a function does use returns they should all have a value, or all with no value. Mixed return usage is likely a bug, or at best poor style.
This rule is defined by the following Java class: net.sourceforge.pmd.lang.ecmascript.rule.bestpractices.ConsistentReturnRule
Example(s):
// Ok
function foo() {
if (condition1) {
return true;
}
return false;
}
// Bad
function bar() {
if (condition1) {
return;
}
return false;
}
This rule has the following properties:
Name | Default Value | Description | Multivalued |
---|---|---|---|
rhinoLanguageVersion | ES6 | Specifies the Rhino Language Version to use for parsing. Defaults to ES6. | no |
recordingLocalJsDocComments | true | Specifies that JsDoc comments are produced in the AST. | no |
recordingComments | true | Specifies that comments are produced in the AST. | no |
Use this rule with the default properties by just referencing it:
<rule ref="category/ecmascript/bestpractices.xml/ConsistentReturn" />
Use this rule and customize it:
<rule ref="category/ecmascript/bestpractices.xml/ConsistentReturn">
<properties>
<property name="rhinoLanguageVersion" value="ES6" />
<property name="recordingLocalJsDocComments" value="true" />
<property name="recordingComments" value="true" />
</properties>
</rule>
GlobalVariable
Since: PMD 5.0
Priority: High (1)
This rule helps to avoid using accidently global variables by simply missing the "var" declaration. Global variables can lead to side-effects that are hard to debug.
This rule is defined by the following XPath expression:
//Assignment[Name/@GlobalName = true()]
Example(s):
function(arg) {
notDeclaredVariable = 1; // this will create a global variable and trigger the rule
var someVar = 1; // this is a local variable, that's ok
window.otherGlobal = 2; // this will not trigger the rule, although it is a global variable.
}
Use this rule by referencing it:
<rule ref="category/ecmascript/bestpractices.xml/GlobalVariable" />
ScopeForInVariable
Since: PMD 5.0
Priority: High (1)
A for-in loop in which the variable name is not explicitly scoped to the enclosing scope with the ‘var’ keyword can refer to a variable in an enclosing scope outside the nearest enclosing scope. This will overwrite the existing value of the variable in the outer scope when the body of the for-in is evaluated. When the for-in loop has finished, the variable will contain the last value used in the for-in, and the original value from before the for-in loop will be gone. Since the for-in variable name is most likely intended to be a temporary name, it is better to explicitly scope the variable name to the nearest enclosing scope with ‘var’.
This rule is defined by the following XPath expression:
//ForInLoop[not(child::VariableDeclaration)]/Name[1]
Example(s):
// Ok
function foo() {
var p = 'clean';
function() {
var obj = { dirty: 'dirty' };
for (var p in obj) { // Use 'var' here.
obj[p] = obj[p];
}
return x;
}();
// 'p' still has value of 'clean'.
}
// Bad
function bar() {
var p = 'clean';
function() {
var obj = { dirty: 'dirty' };
for (p in obj) { // Oh no, missing 'var' here!
obj[p] = obj[p];
}
return x;
}();
// 'p' is trashed and has value of 'dirty'!
}
Use this rule by referencing it:
<rule ref="category/ecmascript/bestpractices.xml/ScopeForInVariable" />
UseBaseWithParseInt
Since: PMD 5.0.1
Priority: High (1)
This rule checks for usages of parseInt. While the second parameter is optional and usually defaults to 10 (base/radix is 10 for a decimal number), different implementations may behave differently. It also improves readability, if the base is given.
See also: parseInt()
This rule is defined by the following XPath expression:
//FunctionCall/Name[
@Image = 'parseInt'
and
count(../*) < 3
]
Example(s):
parseInt("010"); // unclear, could be interpreted as 10 or 7 (with a base of 7)
parseInt("10", 10); // good
Use this rule by referencing it:
<rule ref="category/ecmascript/bestpractices.xml/UseBaseWithParseInt" />