Merge pull request #2954 from eding888/patch-1

Add comma to part1b

Author: mluukkai

src/content/1/en/part1b.md

@@ -457,7 +457,7 @@ const referenceToGreet = arto.greet
 referenceToGreet() // prints "hello, my name is undefined"
 ```
 
-When calling the method through a reference, the method loses knowledge of what the original _this_ was. Contrary to other languages, in JavaScript the value of [this](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this) is defined based on <i>how the method is called</i>. When calling the method through a reference the value of _this_ becomes the so-called [global object](https://developer.mozilla.org/en-US/docs/Glossary/Global_object) and the end result is often not what the software developer had originally intended.
+When calling the method through a reference, the method loses knowledge of what the original _this_ was. Contrary to other languages, in JavaScript the value of [this](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this) is defined based on <i>how the method is called</i>. When calling the method through a reference, the value of _this_ becomes the so-called [global object](https://developer.mozilla.org/en-US/docs/Glossary/Global_object) and the end result is often not what the software developer had originally intended.
 
 Losing track of _this_ when writing JavaScript code brings forth a few potential issues. Situations often arise where React or Node (or more specifically the JavaScript engine of the web browser) needs to call some method in an object that the developer has defined. However, in this course, we avoid these issues by using "this-less" JavaScript.