CODEWITHSUNDEEP
javascriptrecursion
user3477405
user3477405

Reputation: 23

recursion without explicitly setting variable javascript

Here are two working versions (for Node.js) of the same recursive function.

Version 1

function getDependencies(mod, result) {
  result = result || []
  var dependencies = mod.dependencies || []
  Object.keys(dependencies).forEach(function(dep) {
    var key = dep + '@' + mod.dependencies[dep].version
    if (result.indexOf(key) === -1) result.push(key)
    getDependencies(mod.dependencies[dep], result) // COMPARE THIS LINE
  })
  return result.sort()
}

Version 2

function getDependencies(mod, result) {
  result = result || []
  var dependencies = mod.dependencies || []
  Object.keys(dependencies).forEach(function(dep) {
    var key = dep + '@' + mod.dependencies[dep].version
    if (result.indexOf(key) === -1) result.push(key)
    result = getDependencies(mod.dependencies[dep], result) // COMPARE THIS LINE
  })
  return result.sort()
}

How does version 1 of the function work, as compared to version 2, without explicitly setting the result variable?

Upvotes: 0

Views: 74

Answers (1)

Barmar
Barmar

Reputation: 781098

result.push(key) and result.sort() both modify the result array that was passed in as an argument. So there's no need to assign it again in the caller.

Upvotes: 1

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