Added javascript data structures and algorithms (#4625)

* Added javascript data structures and algorithms

* Update free-programming-interactive-tutorials-en.md

free-programming-interactive-tutorials-en.md

@@ -148,6 +148,7 @@
 * [Codecademy jquery track](https://www.codecademy.com/learn/jquery)
 * [ES6 Interactive Guide](http://stack.formidable.com/es6-interactive-guide/#/)
 * [Functional Programming in Javascript](https://github.com/ReactiveX/learnrx)
+* [Javascript Algorithms and Data Structures Certification](https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/basic-javascript) - freeCodeCamp
 * [Javascript interactive tutorial on CodeCademy](https://www.codecademy.com/learn/javascript)
 * [JavaScript interactive tutorial on CoderMania](http://www.codermania.com/javascript/lesson/1a/hello-world)
 * [Javascripting](https://github.com/sethvincent/javascripting)