Simple Example of javascript enumeration Simulation

We will define the Week enumeration as follows:
Copy codeThe Code is as follows:
If (typeof WeekDay = "undefined "){

Var WeekDay = {};

WeekDay. Sunday = 0;

WeekDay. Monday = 1;

WeekDay. Tuesday = 2;

WeekDay. Wedesay = 3;

WeekDay. Thursday = 4;

WeekDay. Friday = 5;

WeekDay. Saturday = 6;

}

The test is as follows:
Alert (WeekDay. Monday); // -----> Output: 1

Of course, we have a more intuitive approach. Taking defining the DOM document node type as an example, the definition is as follows:
Copy codeThe Code is as follows:
If (typeof Node = "undefined "){

Var Node = {

ELEMENT_NODE: 1,

ATTRIBUTE_NODE: 2,

TEXT_NODE: 3,

CDATA_SECTION_NODE: 4,

ENTITY_REFERENCE_NODE: 5,

ENTITY_NODE: 6,

PROCESSING_INSTRUCTION_NODE: 7,

COMMENT_NODE: 8,

DOCUMENT_NODE: 9,

DOCUMENT_TYPE_NODE: 10,

DOCUMENT_FRAGEMENT_NODE: 11,

NOTATION_NODE: 12

}
}

The test is as follows:
Copy codeThe Code is as follows:
Alert (document. nodeType = Node. DOCUMENT_NODE); // -----> Output: true

Note: The preceding Node definition can be used to correct that IE does not support DOM Node type constants (supported by other mainstream browsers ).

Similar to C language, the enumerated values in the preceding two examples are integer values. You might think, can it be defined as another type? To answer this question, we must first understand the principle of enumeration implementation. As mentioned above, JSON is used here, And JSON can use any type of value! Therefore, enumeration in Js can be any type of value. The following uses the String type as an example:
Copy codeThe Code is as follows:
If (typeof Color = "undefined "){

Var Color = {

Color1: 'red ',

Color2: 'green ',

Color3: 'white ',

Color4: 'black'
}
}

The test is as follows:
Alert (Color. Color1); // -----> Output: red

To define a PersonList with a more complex type, the enumeration is as follows:
Copy codeThe Code is as follows:
If (typeof PersonList = "undefined "){

Var PersonList = {

ZhangSan :{

Id: 1,

Name: 'hangsan ',

Gender: 'man'

},

LiSi :{

Id: 2,

Name: 'lisi ',

Gender: 'Woman'

},

ZhaoWu :{

Id: 3,

Name: 'zhaowu ',

Gender: 'man'

}
}
}

The test result is as follows: