Package Exports

tree-visitor-async

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Readme

Tree Visitor Async

Visit nodes in the tree asynchronously and sequentially. Support promises.

Asynchronous version of Tree Visitor. Actions can return a promise and .visit() returns a promise.

Example

var fs = require('fs');
var Q = require('q');
var VisitorAsync = require('tree-visitor-async');

var nodes = [
    { type: 'import', value: 'path/to/file1' },
    { type: 'import', value: 'path/to/file2' },
];
var visitorAsync = new VisitorAsync({
    import: function (importNode) {
        var deferred = Q.defer();
        fs.readFile(importNode.value, 'utf8', function (err, content) {
            if (err) return deferred.reject(err);
            console.log(content);
            deferred.resolve(content);
        });
        return deferred.promise;
    }
});
visitorAsync.visit(nodes).then(function () {
    this === visitorAsync;
    console.log('done');
});

Actions are passed to the returned promise as fulfill callbacks. So, for example, if an action throws an error or returns a rejected promise, subsequent nodes won't be visited.

this keyword in the fulfill callbacks and the reject callbacks refers the visitor object (e.g., visitorAsync in the previous example).