Is the .clear meta-command exactly the same as the .break meta-command, or is it a variation of it? I know that they can both be used to break out of a ... prompt (an indication that you haven't yet finished your command) without exiting the REPL, as can be done by hitting CTRL+C. But are there any fundamental differences between .clear and .break?
I have read in numerous places that in the node.js REPL, the .clear meta-command is meant to wipe out any variables or closures that you might have in memory without the need to restart the REPL.
Is the expected behavior such that I can declare a variable, run the .clear command, and call that variable again, finding it empty/non-declared? In my use of the .clear command, I haven't found that to work.
The .break and .clear commands behave differently depending on if you started the REPL from the node command, or used repl.start().
When using the node command, .clear is just an alias for .break. But if you start the REPL from repl.start(), .clear will then clear the local context as you are expecting, and .break behaves as stated.
This is what .help looks like from a REPL instance started from node:
.break Sometimes you get stuck, this gets you out
.clear Alias for .break
.exit Exit the repl
.help Show repl options
.load Load JS from a file into the REPL session
.save Save all evaluated commands in this REPL session to a file
And this is what it looks like when started programmatically:
.break Sometimes you get stuck, this gets you out
.clear Break, and also clear the local context
.exit Exit the repl
.help Show repl options
.load Load JS from a file into the REPL session
.save Save all evaluated commands in this REPL session to a file
Using .clear in a REPL started with repl.start() will also show this:
Clearing context...
Here's an example of using the REPL programmatically:
var repl = require('repl');
var str = 'We can pass variables into a context.';
repl.start().context.str2 = str;
After this, we have a CLI open. If we type str2 then you will get the contents of str. If you clear the context, then str2 will no longer exist inside the context.
Thanks @hexacyanide for your answer!
And these are two screenshots.
In the first screenshot, REPL was instantiated programmatically (by running the repltest.js script), so the .clear meta-command clears the variable from the memory. You can also see that the .help command returns a different behavior for .clear when REPL is instantiated by a script.
In the second screenshot, .clear has a different behavior however. Here REPL is instantiated directly via command (simply by running node in CMD). In this case, the variables are not cleared from the memory, and the .help command only tells us that .clear is an alias for .break.
Thanks again hexacyanide for clarifying this.