demolish

2019-02-12 admin

demolish是什么

什么是demolish,Generate a destruction method which clean's up and destroys all references on the instance

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demolish

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Demolish is a small module which helps you clean, release and destroy your created instances.

Install

This module is intended for Node.js and Browserify usage and can be installed using:

npm install --save demolish

Usage

The module is exported as a function and be required as following:

'use strict';

var demolish = require('demolish');

The demolish function returns a function which will destroy the specified properties from your instance.

function Foo() {
  this.bar = 1;
  this.banana = new Banana();
}

Foo.prototype.destroy = demolish('bar banana');

In the example above we’ve created a new destroy method on our Foo class. Once the method is called it will set the bar property to null and check if banana also has a destroy method, if so, it will call that method and set the property to null after the execution.

After everything is cleaned up we will emit a destroy event if there is an emit method available.

The destroy method will automatically prevent double execution by checking if the first supplied property is still active on the prototype. So in the example above it will check if bar is not null.

But nulling objects and destroying things you’ve set on an instance might not be enough. Sometimes you need a bit more and for those cases we have the additional before and after hooks. These hooks can be specified in the options:

Foo.prototype.destroy = demolish('bar banana', {
  before: 'clear',
  after: ['removeAllListeners', function () {
    // things
  }]
});

In the example above you see all the supported styles. If you supply a string we assume that it’s a function on the prototype that needs to be executed in order to clean up things correctly. If you need to run multiple tasks you can supply an array with strings. In addition to strings we also support functions, these functions will be called with their this value set to the instance of the class where destroy works.

So in the example above the execution flow is the following:

  1. Check if destroy has already been called, if not, continue to step 2.
  2. Execute the before hook.
  3. Iterate over all properties that need to be destroyed and nulled.
  4. Emit the destroy event, where possible.
  5. Execute the after hook.

License

MIT

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