JS Fundamentals: Objects
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Cory Brown
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var o = new Object();
var o = new SpecializedObjConstructor();
var o = new Object();
var o = {};
var o = Object.create(proto, propDescriptors);
Object
.create(
null,
{
property: {
configurable: false,
enumerable: false,
value: undefined,
writable: false,
get: undefined,
set: undefined
}
}
);`create` is a method on the `Object` constructor.
the first parameter is required and is an object to act as the newly created object's prototype. `null` is also a valid type here.
the second parameter is optional and is an object that defines how the new object's properties are configured.
If false (default:false), any attempts to delete the property or change the `configurable` descriptor will fail. `writable` and `enumerable` can still be changed.
If false (default:false), the property will be NOT iterated over during a for..in (or similar) and will NOT be an item in the array returned by `Object.keys()`
If false (default:false), the value of the property can not be changed.
the value of the property. If set (default:undefined), the `get` and `set` property descriptors must be undefined.
A getter function for the value. If set (default:undefined), the `value` property descriptor must be undefined.
A setter function for the value. If set (default:undefined), the `value` property descriptor must be undefined.
uniqueKey : value
.
.
.{
"twitter": "//twitter.com/uniqname",
"linkedin": "//www.linkedin.com/profile/view?id=21174018",
"github": "//github.com/uniqname"
}that was easy!
Dictionary
Object
A dictionary (associative array, map, symbol table) is a data structure composed of a collection of key, value pairs.
struct date {
int year;
int month;
int day;
};var date = {
year: 1999,
month: 12,
day: 31
};Record
Object
A record (struct, compound data) is a collection of elements, often fixed in number and sequence, indexed by names.
{
"Cory",
"Bruce",
"Daniel"
}{
0: "Cory",
1: "Bruce",
2: "Daniel"
}Set
Object
A data type that stores unordered and unduplicated values.
[value, value, value, ...]{
0: "Cory",
1: "Bruce",
2: "Daniel",
length: 3
}Array
Object
A systematic arrangement of objects, usually in rows and columns