A service worker is an event-driven worker registered against an origin and a path. It takes the form of a JavaScript file that can control the web-page/site that it is associated with, intercepting and modifying navigation and resource requests, and caching resources in a very granular fashion to give you complete control over how your app behaves in certain situations (the most obvious one being when the network is not available).

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Address: 748 Champagne Court, Los Banos, 93635, CA US, +1 209-752-0927

Dynamic Imports
Two similar techniques are supported by webpack when it comes to dynamic code splitting. The first and recommended approach is to use the import() syntax that conforms to the ECMAScript proposal for dynamic imports. The legacy, webpack-specific approach is to use require.ensure. Let's try using the first of these two approaches...

Test verified review

Good UI is necessary to making correct software. If people have trouble using the product, they’re more likely to do the wrong thing. Personally, though, I can’t stand UI work. I don’t think it’s “beneath me” or anything, it just doesn’t quite mesh with my brain. Visuals and interfaces give me anxiety. Mad respect for the people who can handle it.

I love formal methods. Recently my friend Kevin Lynagh released Sketch.systems, a new tool to bring formal specification to UI designers.1 Can my love of formal methods beat my fear of UI? Let’s find out.

# An individual has a phone number

Some people do not own phones, or do not wish to provide you with their telephone number when asked. Do not require a user to provide a phone number unless it is essential, and whenever possible try and provide a fallback to accommodate these users.

# An individual has only one phone number

Obviously, this isn't necessarily true.

# A phone number uniquely identifies an individual

It wasn't even that long ago that mobile phones didn't exist, and it was common for an entire household to share one fixed-line telephone number. In some parts of the world, this is still true, and relatives (or even friends) share a single phone number. Many phone services (especially for businesses) allow multiple inbound calls to or outbound calls from the same phone number.

# Phone numbers cannot be re-used
Old phone numbers are recycled and get reassigned to other people.

Phone numbers that are valid today will always be valid. Phone numbers of a certain type today (e.g., mobile) will never be reassigned to another type.

A phone number which connects today may be disconnected tomorrow. A number which is free to call today may cost money to call tomorrow. The phone company may decide to expand the range of available phone numbers by inserting a digit into an existing number.

Tip: Don’t store properties for a phone number such as validity or type. Check this information again from the library when you need it.

# Each country calling code corresponds to exactly one country

The USA, Canada, and several Caribbean islands share the country calling code +1. Russia and Kazakhstan share +7. These are not the only examples!

# Each country has only one country calling code
As of this present moment (in Mar. 2016), phones in the disputed territory and partially recognised state of Kosovo may be reached by dialing the country calling code for Serbia (+381), Slovenia (+386), or Monaco (+377), depending on where and when one obtained the number.