Workbox-build, empty callbacks for backgroundSync runtimeCaching options

[dandro32]

Hi,
I'm currently working on project based on Create React App v2.1.0 , that includes build-in workbox.
I'm generating a service worker using workbox-build. In runtimeCaching I have several caching options, including backgroundSync option, where I want to include some custom action after queueDidReplay

However, on my generated service worker there is no callback options.

Is this option is available? Or this is CRA issue?
Would be gratefull for any directions or hints.
Thanks.

[jeffposnick]

We do make an attempt to transfer free-form function definitions inside of the runtimeCaching config into the final generated service worker code by using the stringify-object module under the hood, but only for entries in the options.plugins section:

workbox/packages/workbox-build/src/lib/runtime-caching-converter.js

Lines 32 to 38 in b146d8d

	function getOptionsString(options = {}) {
	let plugins = [];
	if (options.plugins) {
	// Using libs because JSON.stringify won't handle functions.
	plugins = options.plugins.map(stringifyWithoutComments);
	delete options.plugins;
	}

When using the shorthands for configuring the various plugins, like options.backgroundSync, we just use JSON.stringify(), which is what's causing what you're seeing:

workbox/packages/workbox-build/src/lib/runtime-caching-converter.js

Lines 75 to 84 in b146d8d

	case 'backgroundSync': {
	const name = pluginConfig.name;
	pluginCode = `new ${pluginString}(${JSON.stringify(name)}`;
	if ('options' in pluginConfig) {
	pluginCode += `, ${JSON.stringify(pluginConfig.options)}`;
	}
	pluginCode += `)`;
	break;
	}

I think switching the JSON.stringify() there to use the same stringify-object wrapper we're using earlier would take care of the issue.

[jeffposnick]

This is fixed in Workbox v4.