text-treeview

node.js library to write a tree hierarchy for console output.

The why

When writing another library I was working with a deep hierarchy of objects that I had to verify.

I iterated the objects and wrote some metadata using space for indenting the lines. But as the hierarchy became more complex it was difficult to follow.

So I wrote a little helper function that could take an array of objects and create a treeview-like experience, making it a lot easer to see the actual structure.

Then I decided it was an excellent little function to share with everyone.

Installation

npm install text-treeview

Basic usage

var tree = require('text-treeview');

console.log(tree([
    {
        text : "Girls",
        children : [
            "Anna",
            "Lisa",
            "Bea"
        ]
    },
    {
        text : "Boys",
        children : [
            "Kalle",
            "Åre",
            "Asgar"
        ]
    }
]));

Will give you the result:

├─ Girls
│  ├─ Anna
│  ├─ Lisa
│  └─ Bea
└─ Boys
   ├─ Kalle
   ├─ Åre
   └─ Asgar

Tree array

Each item in the array must be either a string, or an object with a text property. You can also use the optional children property for an object to add child nodes to the item.

The following snippets will yield identical results:

console.log(tree([
    "Hello",
    "Hej",
    "Hohejoj"
]));

console.log(tree([
    { text : "Hello" },
    { text : "Hej" },
    { text : "Hohejoj" }
]));

Children

Each child item follow the same pattern. A string or the object described above.

console.log(tree([
    {
     text : "Some items",
     children : [
      "Item 1", 
      "Item 2",
      { 
       text : "Item 3",
       children : [ "Item 3.1", "Item 3.2"]
      }
     ]
    }
]));

will give the result

└─ Some items
   ├─ Item 1
   ├─ Item 2
   └─ Item 3
      ├─ Item 3.1
      └─ Item 3.2

Options

You pass the options object as the second parameter. These are only a few options and these are the the default ones.

{
 showRootLines : true,
 format : (indents, treeNode, node) => {
    return `${indents.join('')}${treeNode}${node.text}\n`;
 }
}

• Set showRootLines to false to remove the lines on the root level
• Use format to customize each node. See details below.

format function

format (indents, treeNode, node, parentNode) The format function will create each node and will take four parameters

• indents is an array of each treeview "indent" that will build the treeview.
  • This array contains all the node indicators further up the tree that other levels and nodes in the tree has created.
  • These are either a NODE │ or EMPTY SPACE . These should be joined toghether and put in front of the string.
• treeNode is the actual node indicator for the current node (this is are either a LEAF_NODE (├─ ) or END NODE (└─ ).
• node is the node object
• parentNode is the parent node of the current node

The default function simply looks exactly like this:

function format(indents, treeNode, node) {
    return `${indents.join('')}${treeNode}${node.text}\n`;
}

Change log

• 2021-11-03 - Changed test library and cleaned up references