从子数组中获取父数组

Question

In the code below I can easily enter into a subarray within the array with current = current[0] .

 var root = [ [ 'Value 1', ] ]; var current = root; current = current[0]; current.push('Value 2'); document.write(JSON.stringify(root));

How can I do the reverse and go up a level? In this example, current would become:

[['Value 1', 'Value 2']]

The only way I can think of doing this would be looping, but duplicates would be very probably and problematic. All I've found online is looping, which won't work as a mention in the last sentence.

EDIT

I'm looping through a large string and converting it to a tree. Certain characters will require a indent in the tree or a separate branch, while others will require an outdent and return to the parent function. I've achieved the indents by having a current variable just enter a new subarray as suggested here . I just need a way to exit with a different character.

Answer 1

You can't.

Arrays have no concept of a "parent" or anything. They don't care where their references are being held. However, if you really really need to, you can implement the concept of a "parent" yourself using a simple recursive function setting properties of the arrays - see below:

 var root = [ [ 'Value 1', ] ]; function setParents(root) { for(var i = 0; i < root.length; i++) { if(Array.isArray(root[i])) { root[i].parent = root; setParents(root[i]); } } } setParents(root); var current = root; current = current[0]; current.push('Value 2'); document.write(JSON.stringify(root)); current = current.parent; console.log(current);

This makes use of the fact that array properties don't show up when logged or serialized as JSON, only their elements. So they're kind of "hidden" in a sense. It's a bit hacky but could work for you.

However, I recommend you simply avoid overwriting current - there's not really a great need to use it like a cursor traversing some hierarchy structure.

Answer 2

Simply pushing BEFORE setting current variable will work.

 var root = [ [ 'Value 1', ] ]; var current = root; root.push("AAA"); current = current[0]; current.push('Value 2'); document.write(JSON.stringify(root));