A clearer explanation for recursion and flow of execution in JavaScript?

by

But find didn’t get executed without a value for start and goal. It was first executed with the value 1 for start, and the only value for goal was 24.

Perhaps you’re confused about the order of operations. There we see the declaration of a function, findSequence. During the declaration, no code is executed. The findSequence function only gets executed later, on the last line, where the result of executing the function gets printed out.

Within the declaration of findSequence, there’s a declaration of another function, find. Once again, it doesn’t get executed until later. The findSequence function has just one executable line of code, the one that calls find(1, "1"). Execution of that one line triggers the execution of find some number of times, recursively. The find function makes reference to goal; when the Javascript interpreter executes the code, goal always refers to the parameter of findSequence, and since in this example findSequence is only called once, goal always has the same value, 24.

You should be able to see where the recursion happened. If start was equal to goal, then the function stops; it returns the history of how it arrived at that number. If start is greater than goal, then it returns null, indicating that that path was not a path to the target number. If start is still less than goal, then the function tries calling itself with its start value plus 5. If that returns a non-null value, then that’s what gets returned. Otherwise, it tries multiplying by 3 and returning that history value instead.

Note that although this code can return many numbers, it cannot return all numbers. If the goal is 2, for example, findSequence will return null because there is no way to start at 1 and get to 2 by adding 5 or multiplying by 3.

More Related Contents:

  1. How to write recursive function javascript push my array property Json object?
  2. Javascript a recursive function with no clear base case?
  3. Recursive function returns undefined
  4. How do I replace while loops with a functional programming alternative without tail call optimization?
  5. How does this recursion work?
  6. Recursion in Angular directives
  7. Search recursively for value in object by property name
  8. Typescript recursive function composition
  9. Calling a javascript function recursively
  10. Are functions in JavaScript tail-call optimized?
  11. Recursively print all permutations of a string (Javascript)
  12. javascript: recursive anonymous function?
  13. Maximum call stack size exceeded on SetTimeout recursive function (Javascript) [duplicate]
  14. How to check the depth of an object?
  15. Return value of recursive function is ‘undefined’
  16. Using JavaScript what’s the quickest way to recursively remove properties and values from an object?
  17. Javascript recursive function not returning value?
  18. ES6 Tail Recursion Optimisation Stack Overflow
  19. Understanding Event Queue and Call stack in javascript
  20. Recursive depth function on an array
  21. Why does this recursive function return undefined?
  22. Finding all permutations of array elements as concatenated strings
  23. Javascript – deepEqual Comparison
  24. How to find the least common multiple of a range of numbers?
  25. Jquery Ajax beforeSend and success,error & complete
  26. Await an iterative function without delimiter in JS
  27. How to get all keys with values from nested objects
  28. Recursive tree search in a nested object structure in JavaScript
  29. How does recursive algorithm work for Towers of Hanoi?
  30. javascript return of recursive function [duplicate]

Leave a Comment