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Fugly JavaScript
- 1. Fugly JavaScript Sometimes it’s good to be bad
- 4. Profiling CSI: Front End
- 11. The Good How to make friends and influence people
- 12. Algorithms Sorts Iteration Searches Recursion Filters Functional Programming Caching Object orientation
- 13. Unrolled Loops
- 15. Lookup Tables
- 16. Memoization
- 17. Expressions
- 19. The Evil How to lose friends and alienate people
- 20. Falsey and Truthy Falsey Truthy "" = false "something" = true 0 = false "0" = true undefined = false 1 = true null = false -1 = true
- 22. Comparisons ==, !=, ===, !==, >, >=, <, <=
- 23. Ternary condition ? ifTrue : ifFalse
- 24. Bitwise &, |, ^, ~, <<, >>, >>>
- 25. Know thine enemy
- 26. Number [ digits ][ .digits ][ ( E | e ) [ ( + | - ) ] digits ] x=0 x = -077 x = 123 x = NaN x = -14 x = Number.MAX_VALUE = 1.7976931348623157e+308 x = 0.1541 x = Number.MIN_VALUE = 5e-324 x = NaN x = Number.NEGATIVE_INFINITY x = 0x1123 x = Number.POSITIVE_INFINITY x = -0xF1A7 x = Number.NaN x = 015
- 28. 128 64 32 16 8 4 2 1 1 0 1 1 0 1 0 1 = 181 - 64 32 16 8 4 2 1 1 0 1 1 0 1 0 1 = -53
- 30. Invisible Functions ToInteger ToInt32 ToUint32 ToUint16
- 32. var x = parseInt(x, 10);
- 34. Comma
- 35. Logical OR expression1 || expression2;
- 36. Logical OR
- 37. Logical AND expression1 && expression2;
- 38. Logical AND
Notas del editor
- Some techniques break JSLint rulesOthers look bizarre or daftFine when you’re coding by yourselfRequire good reasons and good explanatory comments in a team environment
- Plenty of tools availableSome even in the browsers
- Doing it wrongTime from beginning to endDoing it rightCount number of iterations
- There is an overhead to looping
- Variation on Duff’s deviceIf we know we have a number of iterations that is a 32 bit number, we can dump the parseInt too
- Dynamically typedDifference between equal and strict equal
- Equal only compares valuesStrict equal compares values AND type
- Returns one of two values based on the logical value of the condition
- Perform functions on values as binary numbersTreat operands as a set of 32 bitsReturn standard numerical values
- Technically a 64-bit number; actually 32-bit when doing anything bitwise.
- Invisible functions
- Converts to an integerConverts to a signed 32-bit integerConverts to an unsigned 32-bit integerConverts to an unsigned 16-bit integer
- Allows multiple expressions to be evaluated in a single statementReturns the result of the last expression
- Returns expr1 if it can be converted to true; otherwise, returns expr2.
- Returns expr1 if it can be converted to false; otherwise, returns expr2.