rspec/rules/S6568/javascript/rule.adoc

The usage of non-null assertion in front of assignments or comparators (``++! =++``, ``++! ==++`` or ``++! ===++``) can be too easily confused with a negative comparison.

The rule raises an issue when ``++! =++``, ``++! ==++`` and ``++! ===++`` are used with a whitespace between the two operators.

== Why is this an issue?

The usage of non-null assertion on the left-hand side of an assignment or comparison can be misread and produce unexpected results when one would expect a negative comparator.

//=== What is the potential impact?

== How to fix it

If you really meant to use the non-null assertion on the variable on which the issue is raised, you can simply move the non-null assertion to another expression, or define a new one.
Otherwise, if an extra whitespace slipped in the middle of a negative comparator, you can simply remove it.

=== Code examples

==== Noncompliant code example

[source,typescript,diff-id=1,diff-type=noncompliant]
----
let foo: number | undefined;
foo = bar! = 12; // Noncompliant; Is that really what's meant?
if (foo! == bar) { // Noncompliant; Is that really what's meant?
  // ...
}
if (foo! === bar) { // Noncompliant; Is that really what's meant?
  // ...
}
----

==== Compliant solution

[source,typescript,diff-id=1,diff-type=compliant]
----
let foo: number | undefined;
foo = bar = 12;
if (foo == bar) {
  // ...
}
if (foo === bar) {
  // ...
}
----

//=== How does this work?

//=== Pitfalls

//=== Going the extra mile


== Resources

=== Documentation

* TypeScript Documentation - https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator-postfix-[Non-null Assertion Operator (Postfix ``++!++``)]

//=== Articles & blog posts
//=== Conference presentations
//=== Standards