Popup script and content script can't communicate?

问题

My problem is that I can't seem to get the message chrome.extension.sendMessage("on"); from my popup.js transfer to my content.js.

Code from the popup.js:

function click(e) {
    if ( e.target.id == "green"){
        chrome.extension.sendMessage("start");
        console.info("oN");
        return;
    }

    if ( e.target.id == "red"){
        chrome.extension.sendMessage("stop");
        console.info("oFF");
        return;
    }
}

The popup.js receives the message perfectly well when i add a listener to the code. But my content.js can't seem to get it.

Code from the content.js:

chrome.extension.onMessage.addListener(
    function(request, sender, sendResponse) {
        console.info("ok");
    }
);

Manifest:

"content_scripts": [
{
    "matches": ["<all_urls>"],
    "js": ["content.js"],
    "run_at": "document_end"
}
],

Any help is greatly appreciated.

回答1:

chrome.extension.sendMessage is a non-canonical name.

The old, deprecated API is chrome.extension.sendRequest, and the new API is chrome.runtime.sendMessage, and the event is likewise chrome.runtime.onMessage.

---

That said, your problem is trying to send a message to a content script. chrome.runtime.sendMessage send messages to extension's own pages; content scripts are not considered such.

To send a message to a content script, you have to use the chrome.tabs.sendMessage API call by tab's tabId.

Assuming you want the current visible tab:

function click(e) {
    if ( e.target.id == "green"){
        chrome.tabs.query({active:true, currentWindow: true}, function(tabs){
            chrome.tabs.sendMessage(tabs[0].id, "start");
        });
        console.info("oN");
        return;
    }
    /* ... */
}

If you want all tabs, just pass {} to query and iterate over tabs.

Finally, take note of content scripts inject time quirks.

来源：https://stackoverflow.com/questions/23992698/popup-script-and-content-script-cant-communicate