Add descriptions to JavaScript Built-In Objects, and Defining Calling Functions (#2111)

content/roadmaps/106-javascript/content/102-javascript-datatypes/101-object/102-builtin-objects.md

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-# Builtin objects
+# Built-in objects
+
+Built-in objects, or "global objects", are those built into the language specification itself. There are numerous built-in objects with the JavaScript language, all of which are accessible at the global scope. Some examples are:
+- `Number`
+- `Math`
+- `Date`
+- `String`
+- `Error`
+- `Function`
+- `Boolean`
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects'>Built-in Objects</BadgeLink>

content/roadmaps/106-javascript/content/109-javascript-functions/100-defining-calling-functions.md

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-# Defining calling functions
+# Defining and Calling Functions
+
+**Defining:** 
+- JavaScript function *declarations* are made by using the `function` keyword.
+- Functions can also be defined by saving function *expressions* to a variable. "Arrow" functions are commonly used in this way.
+
+**Calling:** 
+- When a function is defined, it is not yet executed. 
+- To call and invoke a function's code, use the function's name followed by parentheses: `functionName()`.
+
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+
+<BadgeLink colorScheme='blue' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#defining_functions'>Defining Functions</BadgeLink>
+<BadgeLink colorScheme='blue' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#calling_functions'>Calling Functions</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.w3schools.com/js/js_function_definition.asp'>Function Definitions</BadgeLink>
+
+