Reading-Notes

Class 10 Summary:

Error Handling & Debugging:

Order Of Excution:

• To find the source of an error, it helps to know how scripts are processed. some tasks cannot complete until another statement or function has been run.
• JavaScript interpreter uses the concept of execution cntexts. ther is one execution context and each function creates a new execution context.

The Stack:

• JavaScript process one line of code at a time. when statement need data from a function it stack the new function on the top of the task.

Tow phases of activity when enter a new execution context:

1. Prepare (new scope created, variable and functions created, the value of this keyword determined).
2. Execute (assign values to variables,run functions code,Execute Statements).
   • The error when generated it throws an exception.interpreter stops & looks for exception handling code.

Error Objects:

• can help to find where the mistakes are and there are tools in browsers help to read them.

Error Bojects:

• Syntax Error: incorrect use of the language rules.
• Reference Error:variable that is not declared or is out of scope.
• Type Error:value in unexpected data type.
• Range Error:Number outside of range.

Debugging Workflow:

eliminating potential causes of an error.

Workflow Techniques :

1. Where is the Problem?
2. What Exactly is the Problem?

Script Errors:

1. Go back to basics
2. missed extra characters.
3. Data type Issues.

If we know that we may get an error, we can handle it gracefully using the (try, catch, finally) statements.

Thank You

Sukina AbuHammad