Understanding the JavaScript Call Stack

• What is a ‘call’? At the most basic level, a call stack is a data structure that uses the Last In, First Out (LIFO) principle to temporarily store and manage function invocation (call).

• How many ‘calls’ can happen at once? One call at a time.

• What does LIFO mean? Last in, first out (LIFO).

• Draw an example of a call stack and the functions that would need to be invoked to generate that call stack. function firstFunction(){ console.log(“Hello from firstFunction”); }

function secondFunction(){ firstFunction(); console.log(“The end from secondFunction”); }

secondFunction();

• What causes a Stack Overflow? The most-common cause of stack overflow is excessively deep or infinite recursion, in which a function calls itself so many times that the space needed to store the variables and information associated with each call is more than can fit on the stack.

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JavaScript error messages

• What is a ‘refrence error’? This is as simple as when you try to use a variable that is not yet declared you get this type os errors.

• What is a ‘syntax error’? this occurs when you have something that cannot be parsed in terms of syntax, like when you try to parse an invalid object using JSON.parse.

• What is a ‘range error’? Try to manipulate an object with some kind of length and give it an invalid length and this kind of errors will show up.

• What is a ‘type error’? this types of errors show up when the types (number, string and so on) you are trying to use or access are incompatible, like accessing a property in an undefined type of variable.

• What is a breakpoint? The breakpoint can also be achieved by putting a debugger statement in your code in the line you want to break.

• What does the word ‘debugger’ do in your code? by putting a debugger statement in the code to identify JavaScript errors

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