I have this result [{"recordType":"inventoryitem","id":"19886","values":{"internalid":[{"value":"19886","text":"19886"}]}}] from this, i want to take the internalid value, i tried, but there is no output, could anyone please help me?

What did you try that gave no output?

result[0].values.internalid[0].value

Is this a search object ? If yes result[0].getValue("internalid") will give you value and result[0].getText("internalid") will give you it's text. The 0 after the result may or may not be needed. As there is not enough context provided, if none of those work share your code.