Create rule S6534: Numbers should not lose precision (#1653)

rules/S6534/javascript/metadata.json

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+{
+  "title": "Numbers should not lose precision",
+  "type": "BUG",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+    "numbers",
+    "precision",
+    "floating-point"
+  ],
+  "defaultSeverity": "Major",
+  "ruleSpecification": "RSPEC-6534",
+  "sqKey": "S6534",
+  "scope": "All",
+  "defaultQualityProfiles": ["Sonar way"],
+  "quickfix": "infeasible"
+}

rules/S6534/javascript/rule.adoc

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+
+
+// If you want to factorize the description uncomment the following line and create the file.
+//include::../description.adoc[]
+
+== Why is this an issue?
+
+Numbers in JavaScript are stored as 64-bit floating-point. However, numbers that can't be represented in such a format get rounded before assigning them to a variable.
+
+=== What is the potential impact?
+
+When you are saving a number that is too big or contains a fraction that is not expressible in the 64-bit floating-point format, it gets rounded which will lead to unexpected behaviours when it will be used.
+
+== How to fix it
+
+When you need to store a large number, use `BigInt()`. Pay attention that operations between `BigInt` and `Number` types raise an error, so you will have to adapt your code accordingly.
+
+For numbers with digits after the decimal, it is recommended to use a library to ensure that calculation errors are not introduced by rounding.
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,javascript]
+----
+const foo = 2312123211345545367
+const bar = 0.123456789123456789
+----
+
+==== Compliant solution
+
+[source,javascript]
+----
+const foo = BigInt(2312123211345545367)
+// use a library like decimal.js for storing numbers containing decimal digits
+----
+
+=== How does this work?
+
+JavaScript numbers are stored in a double-precision 64-bit binary format IEEE 754. There are limits to what can be stored in this format both in huge numbers as in numbers with decimal digits.
+When attempting to store a number that can not be represented in this format into a variable, the number gets rounded before storage.
+
+//=== Pitfalls
+
+//=== Going the extra mile
+
+== Resources
+
+=== Documentation
+
+* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number[MDN Number]
+* https://en.wikipedia.org/wiki/Double-precision_floating-point_format[Wikipedia Double-precision floating-point format]
+* https://en.wikipedia.org/wiki/IEEE_754[Wikipedia IEEE 754 Standard]
+
+//=== Articles & blog posts
+//=== Conference presentations
+//=== Standards

rules/S6534/metadata.json

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+{
+}