File Extension File Type Popularity
JSON JavaScript Object Notation Format Very popular ( 5 / 5 )

Variables used in JSON files

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JSON standard is a subset of JavaScript language and thus supports similar variable types

  1. Binary values – boolean type


Boolean expression has one of two values: true or false (which are sometimes represented as integers 1 and 0, respectively). Although it is a simple enough data type, many unexpected errors may arise due to fact that JSON interprets as true the following non-boolean values:

  • any non-zero number type, for example, values 1, -50, or 3.41

  • any non-empty text type, for example “text” , “00”, or even string of value “false”.

  • binary value true


Boolean values false is also given to such values as:

  • number 0

  • number -0 (has no meaning and is resolved to 0)

  • empty text value (“”)

  • any declared variable without any value

  • value null

  • binary value false

  • non-numerical value NaN (for values that cannot be represented as numbers)



  1. Number type – number, integer

    Both types are similar to each other. Integer type is given to integer number values. Number type is given to floating-point numbers and is a dynamic type. Converting number type to integer type implies loss of precision.

  2. Character string type – string

    String is a sequence of zero or more unicode characters, which follows that an empty string value (“” ) is as string of length 0.

  3. Array type – array

    Array is a list of zero or more values of single type, for example, an array containing the names of days of the week.

  4. Object type – object

    Objects can hold any types of data.

  5. Value null

    Value null is not a separate data type, but indicates absence of any value. It is an accepted convention to use null to represent no object value.