source: trip-planner-front/node_modules/are-we-there-yet/README.md@ 6a3a178

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1are-we-there-yet
2----------------
3
4Track complex hiearchies of asynchronous task completion statuses. This is
5intended to give you a way of recording and reporting the progress of the big
6recursive fan-out and gather type workflows that are so common in async.
7
8What you do with this completion data is up to you, but the most common use case is to
9feed it to one of the many progress bar modules.
10
11Most progress bar modules include a rudamentary version of this, but my
12needs were more complex.
13
14Usage
15=====
16
17```javascript
18var TrackerGroup = require("are-we-there-yet").TrackerGroup
19
20var top = new TrackerGroup("program")
21
22var single = top.newItem("one thing", 100)
23single.completeWork(20)
24
25console.log(top.completed()) // 0.2
26
27fs.stat("file", function(er, stat) {
28 if (er) throw er
29 var stream = top.newStream("file", stat.size)
30 console.log(top.completed()) // now 0.1 as single is 50% of the job and is 20% complete
31 // and 50% * 20% == 10%
32 fs.createReadStream("file").pipe(stream).on("data", function (chunk) {
33 // do stuff with chunk
34 })
35 top.on("change", function (name) {
36 // called each time a chunk is read from "file"
37 // top.completed() will start at 0.1 and fill up to 0.6 as the file is read
38 })
39})
40```
41
42Shared Methods
43==============
44
45* var completed = tracker.completed()
46
47Implemented in: `Tracker`, `TrackerGroup`, `TrackerStream`
48
49Returns the ratio of completed work to work to be done. Range of 0 to 1.
50
51* tracker.finish()
52
53Implemented in: `Tracker`, `TrackerGroup`
54
55Marks the tracker as completed. With a TrackerGroup this marks all of its
56components as completed.
57
58Marks all of the components of this tracker as finished, which in turn means
59that `tracker.completed()` for this will now be 1.
60
61This will result in one or more `change` events being emitted.
62
63Events
64======
65
66All tracker objects emit `change` events with the following arguments:
67
68```
69function (name, completed, tracker)
70```
71
72`name` is the name of the tracker that originally emitted the event,
73or if it didn't have one, the first containing tracker group that had one.
74
75`completed` is the percent complete (as returned by `tracker.completed()` method).
76
77`tracker` is the tracker object that you are listening for events on.
78
79TrackerGroup
80============
81
82* var tracker = new TrackerGroup(**name**)
83
84 * **name** *(optional)* - The name of this tracker group, used in change
85 notifications if the component updating didn't have a name. Defaults to undefined.
86
87Creates a new empty tracker aggregation group. These are trackers whose
88completion status is determined by the completion status of other trackers.
89
90* tracker.addUnit(**otherTracker**, **weight**)
91
92 * **otherTracker** - Any of the other are-we-there-yet tracker objects
93 * **weight** *(optional)* - The weight to give the tracker, defaults to 1.
94
95Adds the **otherTracker** to this aggregation group. The weight determines
96how long you expect this tracker to take to complete in proportion to other
97units. So for instance, if you add one tracker with a weight of 1 and
98another with a weight of 2, you're saying the second will take twice as long
99to complete as the first. As such, the first will account for 33% of the
100completion of this tracker and the second will account for the other 67%.
101
102Returns **otherTracker**.
103
104* var subGroup = tracker.newGroup(**name**, **weight**)
105
106The above is exactly equivalent to:
107
108```javascript
109 var subGroup = tracker.addUnit(new TrackerGroup(name), weight)
110```
111
112* var subItem = tracker.newItem(**name**, **todo**, **weight**)
113
114The above is exactly equivalent to:
115
116```javascript
117 var subItem = tracker.addUnit(new Tracker(name, todo), weight)
118```
119
120* var subStream = tracker.newStream(**name**, **todo**, **weight**)
121
122The above is exactly equivalent to:
123
124```javascript
125 var subStream = tracker.addUnit(new TrackerStream(name, todo), weight)
126```
127
128* console.log( tracker.debug() )
129
130Returns a tree showing the completion of this tracker group and all of its
131children, including recursively entering all of the children.
132
133Tracker
134=======
135
136* var tracker = new Tracker(**name**, **todo**)
137
138 * **name** *(optional)* The name of this counter to report in change
139 events. Defaults to undefined.
140 * **todo** *(optional)* The amount of work todo (a number). Defaults to 0.
141
142Ordinarily these are constructed as a part of a tracker group (via
143`newItem`).
144
145* var completed = tracker.completed()
146
147Returns the ratio of completed work to work to be done. Range of 0 to 1. If
148total work to be done is 0 then it will return 0.
149
150* tracker.addWork(**todo**)
151
152 * **todo** A number to add to the amount of work to be done.
153
154Increases the amount of work to be done, thus decreasing the completion
155percentage. Triggers a `change` event.
156
157* tracker.completeWork(**completed**)
158
159 * **completed** A number to add to the work complete
160
161Increase the amount of work complete, thus increasing the completion percentage.
162Will never increase the work completed past the amount of work todo. That is,
163percentages > 100% are not allowed. Triggers a `change` event.
164
165* tracker.finish()
166
167Marks this tracker as finished, tracker.completed() will now be 1. Triggers
168a `change` event.
169
170TrackerStream
171=============
172
173* var tracker = new TrackerStream(**name**, **size**, **options**)
174
175 * **name** *(optional)* The name of this counter to report in change
176 events. Defaults to undefined.
177 * **size** *(optional)* The number of bytes being sent through this stream.
178 * **options** *(optional)* A hash of stream options
179
180The tracker stream object is a pass through stream that updates an internal
181tracker object each time a block passes through. It's intended to track
182downloads, file extraction and other related activities. You use it by piping
183your data source into it and then using it as your data source.
184
185If your data has a length attribute then that's used as the amount of work
186completed when the chunk is passed through. If it does not (eg, object
187streams) then each chunk counts as completing 1 unit of work, so your size
188should be the total number of objects being streamed.
189
190* tracker.addWork(**todo**)
191
192 * **todo** Increase the expected overall size by **todo** bytes.
193
194Increases the amount of work to be done, thus decreasing the completion
195percentage. Triggers a `change` event.
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