Recursion - javascript

Question

I am trying to solve an extra credit problem using recursion. Basically there is a "tree" that has matching "leaves" and I need to use recursion to check those matching leaves and return true if they match and return false if they do not.

I have no idea how to do this and no materials I can find are helping me understand recursion any better. This is for an online program to learn how to program.

Any help would be appreciated!

Psuedo:
 // initialize some value
 // initialize some flag.. boolean
 // initialize some helper function and pass obj...leaf checker recursive function
 // check all the keys ...for loop/forEach
 // if a key is an object && value is undefined
 // assign value
 // return
 // if a value is an object ==> recurse
 // if a value is found and it doesn't match our initial value
 // trip our flag to false
 // return
 // return true or false
 const checkMatchingLeaves = (obj) => {
};

My attempt:

const checkMatchingLeaves = (obj) => {
 // return true if every property on `obj` is the same
 // otherwise return false
 let checker = Object.values(obj);
 if (Object.values(obj).length === 1) return true; 
 if (checker.map(checker[i] === checker[i + 1])) {
 i > checker.length; i++;
 }
};

• Mike Cluck: The absolute basic idea behind recursion is that a function calls itself. Look up the fibonacci function. It's a very common example of a recursive function.
• Jared Smith: @FaizaHusain a recursive function calls itself. Assuming that you have an array full of sub-arrays or primitives you want something like this: const searchTree = (val, tree) => tree.some(node => Array.isArray(node) ? searchTree(node) : val === node); For example searchTree(3, [[1, 2], 4, [[3]]]); returns true and searchTree('abc', ['ab', 'bc', ['a'], [['b']]]); returns false.
• Jared Smith: NOTE: should be searchTree(val, node) in the inner call.

Answer 1

This isn't exactly what (I think) you're asking for, but you should be able to use it as a template to figure out what to do:

// searchTree takes a value to try to match and an array/primitive 
// value.
function searchTree(val, node) {
 // Check if it's a value or an array. If it's a value we can
 // do the test and return, otherwise we recursively call
 // searchTree on all the children.
 // Array.some returns true if any of the function calls return
 // true. This is a shorthand for your boolean flag: it lets us
 // return early as soon as we find a match.
 return Array.isArray(node) ? 
 node.some(child => searchTree(val, child)) : // recursive call
 val === node;
}
searchTree(3, [1, 2, [8], [[[3]]]]); // true
searchTree('abc', 'a'); // false
searchTree('abc', ['ab', 'bc', ['abc']]); // true 

This is a DFS search implementation.