JavaScript – ECMAScript Basics By Satyen
0 likes597 views
This document provides an overview of JavaScript/ECMAScript basics including syntax, variables, data types, operators, and statements. It covers key concepts such as case sensitivity, variable declaration and naming conventions, primitive and reference values, the typeof operator, conversions between data types, built-in objects like String and Number, and unary, arithmetic, comparison, logical, and assignment operators. The document is intended as an introduction to fundamental JavaScript concepts.
JavaScript – ECMAScript Basics By Satyen
- 1. By: Satyen Pandya1JavaScript – ECMAScript [email protected]
- 2. Contents2 Syntax, Variables, Keywords, Reserved Words
- 10. Syntax3 ECMAScript basic concepts :
- 15. Braces indicate code [email protected]
- 16. Variables4 Variables are defined by var operator
- 19. First character must be letter, an underscore (_)\ or dollar sign ($) Remaining characters may be underscores, dollarsings or any alphanumeric characters Variable should follow –
- 22. Hungarian Type Notation (e.g. sMyTest, bMyVar)[email protected]
- 23. Keywords5 Keyword used to indicate beginning and/or endingof statements Keywords are reserved, can not use as variable or function name Few Keywords :[email protected]
- 24. Reserved Words6 Word that are reserved for future use as keyword
- 26. Few Reserved words :[email protected]
- 27. Primitive and Reference Values7Primitive values - simple piece of data, stored on stack, the value is stored directly in location that variable accesses Reference values - objects, stored in heap, the value is stored in variable location – pointer, where the object is [email protected]
- 28. Primitive Types8 ECMAScript has five primitive types :Undefined, Null, Boolean, Number, Stringtypeof Operator used to determine the type variable’svaluetypeof Operator takes one argument
- 29. typeof returns one of below value :
- 30. “undefined”, “boolean”, “number”, “string”, “object”[email protected]
- 31. Conversions9 Type conversion is a short, one-step process in ECMAScript
- 32. Converting to a string : var.toString()
- 33. Converting to a number :var a = parseInt(“123”);var b = parseFloat(“123.456”);Type Casting : Boolean(value); Number(value); String(value);[email protected]
- 34. Reference Types10 They are referred as class, when you have a reference value, you are dealing with an object Objects are created by new operator and class namee.g. varobj = new Object(); Few classes :The Object classThe Boolean classThe Number classThe String classThe instanceof [email protected]
- 35. Reference Types (Contd…)11The object class : base class for all ECMAScript classes
- 37. constructor
- 38. Prototype
- 43. toString()
- 45. Reference Types (Contd…)12The Boolean class : reference type for Boolean type
- 47. toString() – returns true or false
- 48. valueOf() – returns true or false
- 51. toString() – returns number primitive value
- 52. valueOf() – returns number primitive value
- 53. toFixed() – returns string representation of number
- 54. toExponential – returns e-notation string
- 55. toPrecision – returns fixed or e-notation of [email protected]
- 56. Reference Types (Contd…)13The String class : reference type for String type
- 58. toString() – returns string primitive value
- 59. valueOf() – returns string primitive value
- 61. charAt() – returns string containing character in position
- 62. charCodeAt() – returns character code
- 63. concat() – concate two or more strings
- 64. indexOf() – returns position of given substring
- 65. lastindexOf() – returns last position of given substring
- 66. The instanceof operator : identifies the type of [email protected]
- 72. unary plus – returns exact same value for integer, for string it converts them to numbers unary minus – returns negative value for integer, for string it negates the [email protected]
- 74. Bitwise NOT – tilde(~), it works in 3 stpesOperand is converted to 32-bit numberBinary form converted into its one’s complementOne’s complement is converted back to number Bitwise AND – ampersand(&)
- 79. works directly on the binary form of [email protected]
- 84. Logical OR – double pipe(||)[email protected]
- 85. Multiplicative operators18Multiply : represented by asterisk(*)
- 89. Modulus : represented by percent sign(%)[email protected]
- 90. Relational operators19less-than : represented by <
- 93. greater-than-or-equal : represented by >=Equality operatorsEqual : represented by double equal sign (==)
- 95. Identically equal : three equal sign (===)
- 96. Not identically equal : exclamation and two equal (!==)[email protected]
- 97. Conditional operators20 Syntax :Variable = boolean_expression ? true_value : false_value; if expression is true then true_value will be assigned, else false_value will be assignedAssignment operators Simple assignment operator (=) assings the value on the right to the variable on the leftComma operators more than one operation in single [email protected]