rspec/rules/S2392/javascript/rule.adoc

== Why is this an issue?

Variables that are declared inside a block but used outside of it (which is possible with a ``++var++``-style declaration) should be declared outside the block.


=== Noncompliant code example

[source,javascript]
----
function doSomething(a, b) {
  if (a > b) {
    var x = a - b;  // Noncompliant
  }

  if (a > 4) {
    console.log(x);
  }

  for (var i = 0; i < m; i++) { // Noncompliant, both loops use same variable
  }

  for (var i = 0; i < n; i++) {
  }

  return a + b;
}
----


=== Compliant solution

[source,javascript]
----
function doSomething(a, b) {
  var x;

  if (a > b) {
    x = a - b; 
  }

  if (a > 4) {
    console.log(x);
  }

  for (let i = 0; i < m; i++) {
  }

  for (let i = 0; i < n; i++) {
  }


  return a + b;
}
----



ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Consider moving declaration of 'XXX' as it is referenced outside current binding context.


=== Highlighting

* primary: the variable definition
* secondary: every reference to the variable outside of the current binding context.
** message: 'Outside reference.'


'''
== Comments And Links
(visible only on this page)

=== on 26 Jan 2016, 10:51:24 Elena Vilchik wrote:
\[~ann.campbell.2] WDYT if we change this rule to not function scope but to java-like scopes (function+loops+if)?

Following to this convention will ease transition to ES2015 variables declarations (let and const)

=== on 17 Feb 2016, 09:24:03 Elena Vilchik wrote:
\[~ann.campbell.2] I removed part about functions as it probably will produce FP. See

----
var y;   // OK

function foo(p) {
  if (y) {
    bar(y);
  }
  y = p;
}

for (var j = 1; j < 10; j++) {
  foo(j)
}
----

=== on 18 Feb 2016, 09:49:46 Elena Vilchik wrote:
\[~ann.campbell.2] Looks like after removing this "function" thing this rule has not  much in common with RSPEC-1899. May be we should make it as separate RSPEC, WDYT? (cc [~pierre-yves.nicolas])

endif::env-github,rspecator-view[]