CT-answers

1. Every DOM Node has a read-only property named nodeType, i.e. a nodeType valued 3 means it’s a Text node. Given an arbitrary DOM Node, write a function that finds all nested Text nodes and returns them in no particular order as an array.

• answer link

2. An object that has the prototype of a Square function inherits the prototype of a Rectangle function, but of course not all rectangles are squares. Suppose an instance of Rectangle has its own properties width and height changed so that it becomes a square. link

• 2a) What is the condition for a rectangle to also be a square? (not a trick question)
• 2b) How can the Square class inherit the Rectangle class?
• 2c) How can a rectangle instance inherit the Square prototype when it is actually a square?
• 2d) Given a Square instance, how can it lose th e Square prototype when it is no longer a square?

3. A trie (or radix tree, prefix tree) is a tree-like data structure that may be used for efficiently matching a string to a value, for example matching a URL route to a function, which is used for high performance routing. Each branch in this tree is valued by a prefix and a unique value, and this structure continues recursively until there are no more child branches. Given a list of words: "bear", "bears", "bearing", "beer", "boar", write a function that accepts these words as (a, b, ...n) and returns a trie. link

• Here are some considerations:

• A prefix is not necessarily a single character. For example, the given strings will contain the prefixes “ear”, “oar”, “ing”, and “er”. Would sorting the strings in advance simplify processing?

• Bonus a): Write another function that accepts a string and returns either the unique value for a corresponding branch, or undefined if there was no match.

• Bonus b): Explain the advantages and disadvantages of using a trie, versus the more common iteration through a list of regular expressions used for routing in web applications.