CODEWITHSUNDEEP
javascriptgoogle-chrome
temporary_user_name
temporary_user_name

Reputation: 37018

What is "debugger" in a lexical sense?

I just discovered the debugger keyword or whatever it is for JavaScript development, and I'm not clear what it is. Certainly it's not an expression, it has no value. But do I need to put a semi-colon after it? What is it defined as part of? I mean, it's technically like an addition to the language in the chrome runtime, isn't it?

(I know what it does, I just don't know the details of its implementation and how I would explain its lexical nature to someone else.)

Upvotes: 3

Views: 82

Answers (1)

raina77ow
raina77ow

Reputation: 106375

It's actually described in ES5 standard - and yes, it's a statement:

Syntax

DebuggerStatement :

debugger;

Semantics

Evaluating the DebuggerStatement production may allow an implementation to cause a breakpoint when run under a debugger. If a debugger is not present or active this statement has no observable effect.

It is evaluated as follows:

  • If an implementation defined debugging facility is available and enabled, then
    • Perform an implementation defined debugging action.
    • Let result be an implementation defined Completion value.
  • Else
    • Let result be (normal, empty, empty). Return result.

As a sidenote, most modern browsers - not only Chrome - support this functionality.

Upvotes: 6

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