and 3booleans truefalse learn later 2 special

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Unformatted text preview: avaScript primitive types: (1)numbers : whole integers (eg. -3, 0, 104, but not "123") floating-point values (eg. week 3 tutorial3.1416, but not "12.3"), See -0.001, NaN (not a number) Infinity (2)strings of text - Textbox, innerHTML, prompt dialog's result, "...", and `...' (3)booleans (true/false) - learn later! 2 special values (not belong to any one common type): null : means no value. Example: If no element is called 'a', then d o c um e n t.g e tEle m e n tBy Id ('a ') gives null. undefined : means a variable that has been declared but never had a value assigned to it. ie. its value is still undefined. Example: va r x; a le rt(x) ; shows undefined. (CS1301) Introduction to Computer Programming City Univ of HK / Dept of CS / Helena Wong http://www.cs.cityu.edu.hk/~helena 4. Program Structure III - 10 Data Types Numbers Can also be represented as Hexadecimal values: 0x.. or 0X.., eg. var x; x=0xFF; alert(0xFF); eg. var x; x=0123; alert(0123); - set x to 255(10) [ie. 15*16+ 15] - display 255...
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