Is there a way to know if a block is connected in Blockly

[Empe_ldh]

Hello, Thanks for help.

I want to find unconnected, ie unreachable code.

I brought an example to convey it accurately.

Blocks marked with red boxes in the following example are unreachable blocks. 

I wonder if there is a way to detect that block.

further, As in the example, I wonder if it is possible to detect even if an unreachable block is made unreachable by tearing off the entire state where several blocks are connected instead of one.

Waiting for your help.
thank you
Best Regards

[Neil Fraser]

First, you might be looking for this call:

Blockly.getMainworkspace().addChangeListener(Blockly.Events.disableOrphans);

Though that will disable the repeat block in your example, since it's assuming that there would be some sort of 'start' block at the top of the stack.

To answer your question directly, here's some code:

const blocks = Blockly.getMainWorkspace().getTopBlocks(false);

for (const block of blocks) {

  if (block.outputConnection) {

    // This block is unreachable as described in this thread.

  }

}

Note that the current generators will actually generate code for disconnected value blocks -- they aren't unreachable.  In many cases they are harmless, but they might have side effects.

Here's an example:

https://blockly-demo.appspot.com/static/demos/code/index.html#hm4wrx

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Neil Fraser, Switzerland
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