JS

JavaScript book, Ch. 10, “Error Handling & Debugging”

• pg 450
• order of execution, functions, arith, etc
• execution context

  GLOBAL CONTEXT Code that is in the script, but not in a function. There is only one global context in any page.

FUNCTION CONTEXT Code that is being run within a function. Each function has its own function context.

EVAL CONTEXT (NOT SHOWN) Text is executed like code in an internal function called eva l {) (which is not covered in this book).

• Scope

  GLOBAL SCOPE If a variable is declared outside a function, it can be used anywhere because it has global scope. If you do not use the var keyword when creating a variable, it is placed in global scope.

FUNCTION-LEVEL SCOPE When a variable is declared within a function, it can only be used within that function. This is because it has function-level scope.

• THE STACK pg 455 pdf 462

Context Exe

• prepare
• scope create
• var, funcs and args created

• “this” val is determind

• Execute
• assign vals
• ref funcs
• exe statments
• error type tbl pg 459 / 466

how to find consoles and use them for certain browsers (circa2011)

• pg 464 / 471 to pg 470 / 477
• chrome
• IE
• FF
• Opra
• Safari

## stepping through code

• pg 477

throwing errors

• pg 483 / 490

tips

• 484

Common errors

• 485