cropduster

Cropduster

Cropduster is a collection of tools for building pages to be web cropped by Movable Ink.

Installation

Cropduster is on npm. Install it with:

npm install --save-dev cropduster

The use it by importing it from your es6-enabled javascript file:

import CD from 'cropduster';

Legacy Installation

If you are unable to use es6, you can find an es5 version at

http://projects.movableink.com/production/libs/cropduster.[version].js

Where you replace [version] with the version you want to use.

API

Selecting elements

CD.$ is useful for getting an array of DOM elements via a CSS selector. It always returns an array.

Example:

var elements = CD.$('div.items');
for(var i = 0; i < elements.length; i++) {
  var element = elements[i];
  element.style.display = 'none';
}

Query params

CD.param retrieves query parameters from the current document's URL. It does not support nested params or arrays of values.

Example:

// document.location is 'http://example.com/?fname=john
var fname = CD.param('fname');
console.log(fname); // logs 'john'

Fetching third-party resources

Movable Ink's capture engine traditionally captures the web page as soon as the page's ready event fires. This can cause issues when the user tries to fetch pages via ajax, as the capture engine does not wait for the ajax load to complete before rendering. In order to delay capture until the request has finished, use CD.get. It temporarily suspends capture until the request completes. Note: the URL has to be CORS-accessible, see CD.getCORS if it isn't. When in doubt, use CD.getCORS.

Example:

CD.get('http://cors-enabled-site.com/page', function(data, status) {
  CD.$('h1')[0].innerHTML = data.header;
});

Send POST and sending extra headers:

CD.get('http://cors-enabled-site.com/page', {
  method: 'POST',
  body: '{"ok": "yes"}',
  headers: {
    'Accept': 'application/json'
  }
}, function(data, status) {
  CD.$('h1')[0].innerHTML = data.h1;
})

Fetching third-party resources with CORS

Security restrictions prevent web pages from making cross-domain ajax requests. CORS is a workaround, but requires support from the website, and many websites do not support it. Instead, use CD.getCORS to use Movable Ink's CORS proxy to access the page.

Example:

CD.getCORS('http://example.com/page', function(data, status) {
  CD.$('h1')[0].innerHTML = data.header;
});

Fetching images

Deprecated: The CD.getImage() and CD.getImages() calls have been superseded by CD.waitForAsset(). They will continue to work for the foreseeable future, but CD.waitForAsset is preferred.

CD.waitForAsset ensures that in-flight requests for a particular asset URL complete before capturing the page. CD.waitForAsset does not fetch the image, that is up to you to do however you may normally do it. If the image is not loading ("in-flight") when capturama tries to capture the page, there will be no impact. It can be called any time before page capture. CD.waitForAsset is compatible with <img> tags, css background-image properties, and any other way an image is loaded into a webpage.

Example:

CD.$('.background')[0].style.backgroundImage = 'url(http://example.com/foo.png)';
CD.waitForAsset('http://example.com/foo.png');

Redirecting to another image

Sometimes, it is necessary to redirect to an image rather than rendering dynamic content. For example, a countdown timer may want to just show an image after the countdown has expired. It is certainly possible to just render the image inside the webpage and crop that, but a better solution is to use CD.setImageRedirect to issue a 302 redirect to the user to send them to the static content. If the function is called multiple times, the last image URL called is used.

Example:

CD.setImageRedirect('http://example.com/foo.png');
console.log('user will be shown image located at http://example.com/foo.png');

Storing extra analytics data

It is possible to store extra data using the CD.setExtraData call. This data will be available in the extra_data field of the User-level Reports. Pass a javascript object, and it will be turned into JSON and stored in extra_data. Calling multiple times results in the objects being combined and any duplicate keys overwritten.

Example:

CD.setExtraData({userId: 5});
CD.setExtraData({shownCategory: 'shoes'});
console.log('extra_data field now contains {"userId":5,"shownCategory":"shoes"}');

Setting custom per-user clickthrough URLs

When showing dynamic content, it may be useful to be able to associate dynamic content with matching clickthroughs. Using CD.setClickthrough, you can save a clickthrough URL that users will visit when they click on the web crop. In order to work properly, the query params on both the embed code's image and link must match. If called multiple times, only the last called clickthrough URL will be used.

Example:

CD.setClickthrough('http://example.com');
console.log('If user clicks on the web crop, they will go to http://example.com');

Testing

brew install phantomjs
npm install
npm test

Changelog

4.0.0

• Switch from bower to npm; CD is now exported as es6 module. See the new installation instructions above.

3.4.2

• Remove bower from npm postinstall, for npm usage.

3.4.1

• Adds CD.params(), returning an object with all parameters.

3.4.0

• Exposes the content-type response header within the callback of CD.get().

3.3.0

• Add support for CD.waitForAsset(). This API can be used to ensure that we will not render while the passed URL is in-flight.

3.2.3

• fix bower/npm version numbers

3.2.2

• Ensure that CD.suspend(msg) always logs the msg string

3.2.1

• CD.get() and CD.getCORS() return the (integer) http status as the second argument of their callbacks. This is currently completely backwards-compatible, but we would like to make backwards-incompatible changes to this API in the future.

3.2.0

• Support CD.cancelRequest(msg) for when crop wants to show fallback but not trigger error condition
• Support CD.throwError(msg) for when crop fails (such as XHR failure) and trigger error
• CD.begin(msg) and CD.end(msg) support an argument that will be logged for easier debugging

3.1.1

• Support for CD.getCORS() with non-standard ports

3.1.0

• CD.getCORS() sends x-mi-cbe request header to ensure requests consistently go to the same backend

3.0.0

• No more reference counting or maxSuspensions
• CD.getImages() accepts two callbacks, one for when all images resolve and once for after each image resolves

2.7.3

• CD.capture forces a redraw on the page

2.7.2

• Ensure that CD.getImages actually suspends crop

2.7.1

• Remove window.onerror handler
• Ensure that failing requests actually call callback with null, rather than empty string

2.7.0

• Failing requests call the callback with null.
• Do not pass cors ttl headers on regular get request.

2.6.0

• Add get to fetch resources without using CORS

2.5.0

• Add setImageRedirect, setClickthrough, and setExtraData
• Set up TravisCI test suite

2.4.0

• New options for CD.getCORS: method for changing HTTP method, body for sending request body when POST method is used, and headers object for sending extra request headers.

2.3.0

• Guarantee correct ordering of callbacks in getImages()

License

Copyright © 2015 Movable, Inc

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.