Injecting multiple scripts through executeScript in Google Chrome

Question

I need to programmatically inject multiple script files (followed by a code snippet) into the current page from my Google Chrome extension. The chrome.tabs.executeScript method allows for a single InjectDetails object (representing a script file or code snippet), as well as a callback function to be executed after the script. Current answers propose nesting executeScript calls:

chrome.browserAction.onClicked.addListener(function(tab) {
    chrome.tabs.executeScript(null, { file: "jquery.js" }, function() {
        chrome.tabs.executeScript(null, { file: "master.js" }, function() {
            chrome.tabs.executeScript(null, { file: "helper.js" }, function() {
                chrome.tabs.executeScript(null, { code: "transformPage();" })
            })
        })
    })
});

However, the callback nesting gets unwieldy. Is there a way of abstracting this?

Answer 1

This is my proposed solution:

function executeScripts(tabId, injectDetailsArray)
{
    function createCallback(tabId, injectDetails, innerCallback) {
        return function () {
            chrome.tabs.executeScript(tabId, injectDetails, innerCallback);
        };
    }

    var callback = null;

    for (var i = injectDetailsArray.length - 1; i >= 0; --i)
        callback = createCallback(tabId, injectDetailsArray[i], callback);

    if (callback !== null)
        callback();   // execute outermost function
}

Subsequently, the sequence of InjectDetails scripts can be specified as an array:

chrome.browserAction.onClicked.addListener(function (tab) {
    executeScripts(null, [ 
        { file: "jquery.js" }, 
        { file: "master.js" },
        { file: "helper.js" },
        { code: "transformPage();" }
    ])
});

Answer 2

From Chrome v32, it supports Promise. We should use it for making code clean.

Here is an example:

new ScriptExecution(tab.id)
    .executeScripts("js/jquery.js", "js/script.js")
    .then(s => s.executeCodes('console.log("executes code...")'))
    .then(s => s.injectCss("css/style.css"))
    .then(s => console.log('done'));

ScriptExecution source:

(function() {
    function ScriptExecution(tabId) {
        this.tabId = tabId;
    }

    ScriptExecution.prototype.executeScripts = function(fileArray) {
        fileArray = Array.prototype.slice.call(arguments); // ES6: Array.from(arguments)
        return Promise.all(fileArray.map(file => exeScript(this.tabId, file))).then(() => this); // 'this' will be use at next chain
    };

    ScriptExecution.prototype.executeCodes = function(fileArray) {
        fileArray = Array.prototype.slice.call(arguments);
        return Promise.all(fileArray.map(code => exeCodes(this.tabId, code))).then(() => this);
    };

    ScriptExecution.prototype.injectCss = function(fileArray) {
        fileArray = Array.prototype.slice.call(arguments);
        return Promise.all(fileArray.map(file => exeCss(this.tabId, file))).then(() => this);
    };

    function promiseTo(fn, tabId, info) {
        return new Promise(resolve => {
            fn.call(chrome.tabs, tabId, info, x => resolve());
        });
    }


    function exeScript(tabId, path) {
        let info = { file : path, runAt: 'document_end' };
        return promiseTo(chrome.tabs.executeScript, tabId, info);
    }

    function exeCodes(tabId, code) {
        let info = { code : code, runAt: 'document_end' };
        return promiseTo(chrome.tabs.executeScript, tabId, info);
    }

    function exeCss(tabId, path) {
        let info = { file : path, runAt: 'document_end' };
        return promiseTo(chrome.tabs.insertCSS, tabId, info);
    }

    window.ScriptExecution = ScriptExecution;
})()

If you would like to use ES5, you can use online compiler to compile above codes to ES5.

Fork me on GitHub: chrome-script-execution

Answer 3

Given your answer, I expected synchronously injecting the scripts to cause problems (namely, I thought that the scripts might be loaded in the wrong order), but it works well for me.

var scripts = [
  'first.js',
  'middle.js',
  'last.js'
];
scripts.forEach(function(script) {
  chrome.tabs.executeScript(null, { file: script }, function(resp) {
    if (script!=='last.js') return;
    // Your callback code here
  });
});

This assumes you only want one callback at the end and don't need the results of each executed script.

Answer 4

This is mostly an updated answer (on the other answer) :P

const executeScripts = (tabId, scripts, finalCallback) => {
  try {
    if (scripts.length && scripts.length > 0) {
      const execute = (index = 0) => {
        chrome.tabs.executeScript(tabId, scripts[index], () => {
          const newIndex = index + 1;
          if (scripts[newIndex]) {
            execute(newIndex);
          } else {
            finalCallback();
          }
        });
      }
      execute();
    } else {
      throw new Error('scripts(array) undefined or empty');
    }
  } catch (err) {
    console.log(err);
  }
}

executeScripts(
  null, 
  [
    { file: "jquery.js" }, 
    { file: "master.js" },
    { file: "helper.js" },
    { code: "transformPage();" }
  ],
  () => {
    // Do whatever you want to do, after the last script is executed.
  }
)

Or return a promise.

const executeScripts = (tabId, scripts) => {
  return new Promise((resolve, reject) => {
    try {
      if (scripts.length && scripts.length > 0) {
        const execute = (index = 0) => {
          chrome.tabs.executeScript(tabId, scripts[index], () => {
            const newIndex = index + 1;
            if (scripts[newIndex]) {
              execute(newIndex);
            } else {
              resolve();
            }
          });
        }
        execute();
      } else {
        throw new Error('scripts(array) undefined or empty');
      }
    } catch (err) {
      reject(err);
    }
  });
};

executeScripts(
  null, 
  [
    { file: "jquery.js" }, 
    { file: "master.js" },
    { file: "helper.js" },
    { code: "transformPage();" }
  ]
).then(() => {
  // Do whatever you want to do, after the last script is executed.
})

Answer 5

Fun fact, the scripts are injected in order and you don't need to wait for each one to be injected.

chrome.browserAction.onClicked.addListener(tab => {
    chrome.tabs.executeScript(tab.id, { file: "jquery.js" });
    chrome.tabs.executeScript(tab.id, { file: "master.js" });
    chrome.tabs.executeScript(tab.id, { file: "helper.js" });
    chrome.tabs.executeScript(tab.id, { code: "transformPage();" }, () => {
        // All scripts loaded
    });
});

This is considerably faster than manually waiting for each one. You can verify that they are loaded in order by loading a huge library first (like d3.js) and then loading a small file after. The order will still be preserved.

Note: errors aren't caught, but this should never happen if all files exist.

---

If you want to catch the errors, I'd suggest to use the Firefox’ browser.* APIs with their Chrome polyfill

browser.browserAction.onClicked.addListener(tab => {
    Promise.all([
        browser.tabs.executeScript(tab.id, { file: "jquery.js" }),
        browser.tabs.executeScript(tab.id, { file: "master.js" }),
        browser.tabs.executeScript(tab.id, { file: "helper.js" }),
        browser.tabs.executeScript(tab.id, { code: "transformPage();" })
    ]).then(() => {
        console.log('All scripts definitely loaded')
    }, error => {
        console.error(error);
    });
});