The value of this variable is undefined using a Var declared variable but does not initialize it.
Undefined type The undefined type has only one value, ie undefined. Finally, after assigning this object to the variable xiaoming, you can obtain xiaoming's attributes through the variable xiaoming: xiaoming.name // 'Xiao Ming'Īccess properties through Operator, but this requires that the property name must be a valid variable name. There are five simple data types in Ecmascript (basic data types): undefined, null, boolean, number, string. The above object declares a name attribute, the value is xiaoming, the birth attribute, the value is 1990, and some other attributes. If it is added, some browsers (such as lower versions of IE) will report an error. In JavaScript, we have various data types like: Number String Boolean Arrays Object null undefined The typeof () function can be used to see the data type of the variable. They define the type of data a variable can hold. Note that the last key value pair does not need to be added at the end. Data Types are important concepts in any language. JSONs basic data types are: Number: a signed decimal number that may contain a fractional part and may use exponential E notation, but cannot include non-numbers such as NaN.The format makes no distinction between integer and floating-point. Key value pairs are declared in the form of xxx: xxx, separated by. JSON became a strict subset of ECMAScript as of the languages 2019 revision. Each of these data types is a different topic in itself. these types are basic data types but are very powerful because data structures in JavaScript are built using. The non-primitive datatypes in JavaScript include objects, arrays, and functions. But in basic terms, selecting the right data type for the right application is important. Object that represents a dataset of composite structures Data types are also a relevant topic for data structures, which is for more advanced programmers. data typeĪn undefined value that represents an unassigned initialization valueīoolean value, the value of a logical operation JavaScript defines six basic data types, as shown in the table.
#JAVASCRIPT BASIC DATA TYPES PLUS#
Simple values (raw values): contains strings, numbers, and Boolean values, plus two special values - null (null) and undefined (defined as).Ĭomplex data structures (generally referred to as objects): including narrow objects, arrays and functions.
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