Async-traverse

A utility library for asynchronous traversal and delegated recursion.

• Example

API

The async-traverse package exports a factory function for custom traversal implementations.

var traverser = require('async-traverse');

Provide a callback function with signature node, next, and a traversal function will be returned.

var traverser = require('async-traverse');

var t = traverser(function(node, next) {
  console.log(node);
  next();
});

//t is your custom traverser.

Pass an array to the provided function, and it will begin to execute your callback, passing it at each iteration the current node, and a next function. Each time your code calls the next() function (and passes no parameters), your callback will be called again with the next object.

If your code passes an array, next(someArray), then the traverser will iterate over each someArray item before returning to its previous items. This allows you to make the decision asynchronously as to whether recursion needs to happen, and control which items will be processed asynchronously.

• Recurse on any property
• Wait for user input before continuing
• Check with an asynchronous service before recursing

The initial call to your returned function, t(someData), will return a promise for the completed traversal of the tree. The promise is resolved when there are no more items to process.

var traverser = require('async-traverse');

var t = traverser(function(node, next) {
  console.log(node);
  next();
});

//t is your custom traverser.

Example

var traverser = require('async-traverse')

var tree = [{
    id: 1,
    children: [{
        id: 2,
        children: [{
            id: 3
        }]
    }]
},{
    id: 4,
    children: [{
        id: 5,
        children: [{
            id: 6
        }]
    }]
}];

var current, continue;

var t = traverser(function(node, next) {
    current = node;
    continue = next;
});

t(tree).then(function() {
  console.log('Done!');
});

console.log(current); // {id: 1, children: [...]}

//Call next to go to the next node.
next();

console.log(current); // {id: 4, children: [...]}

//Call next with an array of children to iterate over those children before
//continuing to the next node (or finishing if no nodes left);

next(current.children);

console.log(current); // {id: 5, children: [{id: 6}]}

next(current.children);

console.log(current); // {id: 6}

next(); //No nodes left at any level; promise will be resolved

// 'Done!' (logged by above promise);