define

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2023-12-01

Create a new constructor function for a type inheriting from ObjectLikeSequence.

Signature

ObjectLikeSequence.define = function(methodName, overrides) { /*...*/ }

ObjectLikeSequence.define = function define(methodName, overrides) {
  if (!overrides || typeof overrides.each !== 'function') {
throw new Error("A custom object-like sequence must implement *at least* each!");
  }

  return defineSequenceType(ObjectLikeSequence, methodName, overrides);
}

Name	Type(s)	Description
methodName	string\|Array.<string>	The name(s) of the method(s) to be used for constructing the new sequence. The method will be attached to the `ObjectLikeSequence` prototype so that it can be chained with any other methods that return object-like sequences.
overrides	Object	An object containing function overrides for this new sequence type. Must include `each`. May include `init` and `get` (for looking up an element by key).
returns	Function	A constructor for a new type inheriting from `ObjectLikeSequence`.

Examples

function downcaseKey(value, key) {
  return [key.toLowerCase(), value];
}

Lazy.ObjectLikeSequence.define("caseInsensitive", {
  init: function() {
var downcased = this.parent
  .map(downcaseKey)
  .toObject();
this.downcased = Lazy(downcased);
  },

  get: function(key) {
return this.downcased.get(key.toLowerCase());
  },

  each: function(fn) {
return this.downcased.each(fn);
  }
});

Lazy({ Foo: 'bar' }).caseInsensitive()            // sequence: { foo: 'bar' }
Lazy({ FOO: 'bar' }).caseInsensitive().get('foo') // => 'bar'
Lazy({ FOO: 'bar' }).caseInsensitive().get('FOO') // => 'bar'