Microsoft® JScript™ Data Type Conversion | Language Reference Version 3

##### Description

> Microsoft JScript provides automatic type conversion as the context may require. This means that if the context expects a value to be a string, for example, JScript tries to convert the value to a string.

> The language has six types of data. All values have one of these types:

> > undefined
> >   The undefined type has one value only, undefined.
> > Null
> >   The null type has one value only, null.
> > Boolean
> >   The Boolean type represents the two logical values, true and false.
> > String
> >   Strings, delineated by single or double quotation marks, contain zero or more Unicode characters. An empty string ("") has zero characters and length.
> > Number
> >   Numbers can be integers or floating-point numbers according to the IEEE 754 specification. There also several special values:
> >   - NaN, or not a Number
> >   - Positive Infinity
> >   - Negative Infinity
> >   - Positive zero
> >   - Negative zero
> > Object
> >   An Object type is an object definition including its set of properties and methods.

> The following table defines what happens when the context requires that JScript convert one data type into another:

> Output Data Type | Input Data Type
> Undefined | Null | Boolean | Number | String | Object
> boolean | false | false | no conversion | false if +0, -0, or NaN; otherwise true | false if empty string (""); otherwise true | true
> number | NaN | NaN | 1 if true; +0 if false | no conversion | If it cannot be interpreted as a number, it is interpreted as NaN | Number object
> string | "undefined" | "null" | "true" or "false" | The absolute value of the number plus its sign, with the following exceptions:
> - NaN returns "NaN"
> - +0 or -0 returns "0"
> - + infinity returns "Infinity"
> - - infinity returns "-Infinity"
> no conversion
> String object
> object | run-time error | run-time error | New Boolean object | New Number object | New String object | no conversion

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