// The ID of the extension we want to talk to. var laserExtensionId = "abcdefghijklmnoabcdefhijklmnoabc"; // Make a simple request: chrome.runtime.sendMessage(laserExtensionId, {getTargetData: true}, function(response) { if (targetInRange(response.targetData)) chrome.runtime.sendMessage(laserExtensionId, {activateLasers: true}); } ); // Start a long-running conversation: var port = chrome.runtime.connect(laserExtensionId); port.postMessage(...);