我正在使用webExtensions开发 firefox 扩展程序，这有助于我轻松完成下面的方案。
我必须点击网站上大约50-60个按钮来更新任务状态。单击此按钮，网页将调用网页的updTask(id) JavaScript函数，然后进行Web服务调用以更新任务。
我无法使用以下代码从我的内容脚本中执行此操作：
的manifest.json ：
"permissions": [
"activeTab",
"cross-domain-content": ["http://workdomain.com/","http://workdomain.org/","http://www.workdomain.com/","http://www.workdomain.org/"]
]
内容 - 脚本代码：
function taskUpdate(request, sender, sendResponse) {
console.log(request.start + 'inside task update');
updateTask(45878);
chrome.runtime.onMessage.removeListener(taskUpdate);
}
function updateTask(id) {
//TODO: code to get all buttons and task id's
updTask(id); // Not working
}
插件脚本：
document.addEventListener("click", function(e) {
if (e.target.classList.contains("startButton")) {
chrome.tabs.executeScript(null, {
file: "/content_scripts/taskUpdate.js"
});
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
chrome.tabs.sendMessage(tabs[0].id, {start: "start"});
});
return;
}
else if (e.target.classList.contains("clear")) {
chrome.tabs.reload();
window.close();
return;
}
});
有人能指出我正确的方向，我在这里错过了什么？
答案 0 :(得分：3)
您的内容脚本与页面脚本（网页中已存在的脚本）的上下文/范围不同。您的内容脚本具有比授予页面脚本更高的权限。保持内容脚本与页面脚本分离是浏览器扩展的常规体系结构，出于安全原因这样做。
为了在页面脚本上下文中执行代码，您必须在页面的DOM中创建并插入<script>元素。
您可以执行以下操作：
function updateTask(id) {
let newScript = document.createElement('script');
newScript.innerHTML='updTask(' + id + ');';
document.head.appendChild(newScript);
//newScript.remove(); //Can be removed, if desired.
}
添加的脚本在页面上下文中运行，因为它现在是DOM中的<script>元素。浏览器识别出添加了<script>元素并在插入它的脚本不再处理时对其进行评估（执行包含的代码）。对于添加到DOM的任何其他元素，它基本上都是一样的。因为它是页面的一部分，所以gets里面的代码在页面脚本上下文/范围中运行。
维护要在页面上下文中执行的代码的最简单方法是将其作为函数写入内容脚本，然后将该函数注入页面上下文。下面是一些通用代码，它们将参数传递给您在页面上下文中执行的函数时执行此操作：
此实用程序函数executeInPage()将在页面上下文中执行一个函数，并将任何提供的参数传递给函数。参数必须为Object，Array，function，RegExp，Date和/或其他primitives（Boolean，{ {3}}，null，undefined，Number，但不是String）。
/* executeInPage takes a function defined in this context, converts it to a string
* and inserts it into the page context inside a <script>. It is placed in an IIFE and
* passed all of the additional parameters passed to executeInPage.
* Parameters:
* func The function which you desire to execute in the page.
* leaveInPage If this does not evaluate to a truthy value, then the <script> is
* immediately removed from the page after insertion. Immediately
* removing the script can normally be done. In some corner cases,
* it's desirable for the script to remain in the page. However,
* even for asynchronous functionality it's usually not necessary, as
* the context containing the code will be kept with any references
* (e.g. the reference to a callback function).
* id If this is a non-blank string, it is used as the ID for the <script>
* All additional parameters are passed to the function executing in the page.
* This is done by converting them to JavaScript code-text and back.
* All such parameters must be Object, Array, functions, RegExp,
* Date, and/or other primitives (Boolean, null, undefined, Number,
* String, but not Symbol). Circular references are not supported.
* If you need to communicate DOM elements, you will need to
* pass selectors, or other descriptors of them (e.g. temporarily
* assign them a unique class), or otherwise communicate them to the
* script (e.g. you could dispatch a custom event once the script is
* inserted into the page context).
*/
function executeInPage(functionToRunInPage, leaveInPage, id) {
//Execute a function in the page context.
// Any additional arguments passed to this function are passed into the page to the
// functionToRunInPage.
// Such arguments must be JSON-ifiable (also Date, Function, and RegExp) (prototypes
// are not copied).
// Using () => doesn't set arguments, so can't use it to define this function.
// This has to be done without jQuery, as jQuery creates the script
// within this context, not the page context, which results in
// permission denied to run the function.
function convertToText(args) {
//This uses the fact that the arguments are converted to text which is
// interpreted within a <script>. That means we can create other types of
// objects by recreating their normal JavaScript representation.
// It's actually easier to do this without JSON.strigify() for the whole
// Object/Array.
var asText = '';
var level = 0;
function lineSeparator(adj, isntLast) {
level += adj - ((typeof isntLast === 'undefined' || isntLast) ? 0 : 1);
asText += (isntLast ? ',' : '') +'\n'+ (new Array(level * 2 + 1)).join('');
}
function recurseObject(obj) {
if (Array.isArray(obj)) {
asText += '[';
lineSeparator(1);
obj.forEach(function(value, index, array) {
recurseObject(value);
lineSeparator(0, index !== array.length - 1);
});
asText += ']';
} else if (obj === null) {
asText +='null';
//undefined
} else if (obj === void(0)) {
asText +='void(0)';
//Special cases for Number
} else if (Number.isNaN(obj)) {
asText +='Number.NaN';
} else if (obj === 1/0) {
asText +='1/0';
} else if (obj === 1/-0) {
asText +='1/-0';
//function
} else if (obj instanceof RegExp || typeof obj === 'function') {
asText += obj.toString();
} else if (obj instanceof Date) {
asText += 'new Date("' + obj.toJSON() + '")';
} else if (typeof obj === 'object') {
asText += '{';
lineSeparator(1);
Object.keys(obj).forEach(function(prop, index, array) {
asText += JSON.stringify(prop) + ': ';
recurseObject(obj[prop]);
lineSeparator(0, index !== array.length - 1);
});
asText += '}';
} else if (['boolean', 'number', 'string'].indexOf(typeof obj) > -1) {
asText += JSON.stringify(obj);
} else {
console.log('Didn\'t handle: typeof obj:', typeof obj, ':: obj:', obj);
}
}
recurseObject(args);
return asText;
}
var newScript = document.createElement('script');
if(typeof id === 'string' && id) {
newScript.id = id;
}
var args = [];
//using .slice(), or other Array methods, on arguments prevents optimization
for(var index=3;index<arguments.length;index++){
args.push(arguments[index]);
}
newScript.textContent = '(' + functionToRunInPage.toString() + ').apply(null,'
+ convertToText(args) + ");";
(document.head || document.documentElement).appendChild(newScript);
if(!leaveInPage) {
//Synchronous scripts are executed immediately and can be immediately removed.
//Scripts with asynchronous functionality of any type must remain in the page
// until complete.
document.head.removeChild(newScript);
}
return newScript;
};
excuteInPage()：
function logInPageContext(arg0,arg1,arg2,arg3){
console.log('arg0:', arg0);
console.log('arg1:', arg1);
console.log('arg2:', arg2);
console.log('arg3:', arg3);
}
executeInPage(logInPageContext, false, '', 'This', 'is', 'a', 'test');
/* executeInPage takes a function defined in this context, converts it to a string
* and inserts it into the page context inside a <script>. It is placed in an IIFE and
* passed all of the additional parameters passed to executeInPage.
* Parameters:
* func The function which you desire to execute in the page.
* leaveInPage If this does not evaluate to a truthy value, then the <script> is
* immediately removed from the page after insertion. Immediately
* removing the script can normally be done. In some corner cases,
* it's desirable for the script to remain in the page. However,
* even for asynchronous functionality it's usually not necessary, as
* the context containing the code will be kept with any references
* (e.g. the reference to a callback function).
* id If this is a non-blank string, it is used as the ID for the <script>
* All additional parameters are passed to the function executing in the page.
* This is done by converting them to JavaScript code-text and back.
* All such parameters must be Object, Array, functions, RegExp,
* Date, and/or other primitives (Boolean, null, undefined, Number,
* String, but not Symbol). Circular references are not supported.
* If you need to communicate DOM elements, you will need to
* pass selectors, or other descriptors of them (e.g. temporarily
* assign them a unique class), or otherwise communicate them to the
* script (e.g. you could dispatch a custom event once the script is
* inserted into the page context).
*/
function executeInPage(functionToRunInPage, leaveInPage, id) {
//Execute a function in the page context.
// Any additional arguments passed to this function are passed into the page to the
// functionToRunInPage.
// Such arguments must be JSON-ifiable (also Date, Function, and RegExp) (prototypes
// are not copied).
// Using () => doesn't set arguments, so can't use it to define this function.
// This has to be done without jQuery, as jQuery creates the script
// within this context, not the page context, which results in
// permission denied to run the function.
function convertToText(args) {
//This uses the fact that the arguments are converted to text which is
// interpreted within a <script>. That means we can create other types of
// objects by recreating their normal JavaScript representation.
// It's actually easier to do this without JSON.strigify() for the whole
// Object/Array.
var asText = '';
var level = 0;
function lineSeparator(adj, isntLast) {
level += adj - ((typeof isntLast === 'undefined' || isntLast) ? 0 : 1);
asText += (isntLast ? ',' : '') +'\n'+ (new Array(level * 2 + 1)).join('');
}
function recurseObject(obj) {
if (Array.isArray(obj)) {
asText += '[';
lineSeparator(1);
obj.forEach(function(value, index, array) {
recurseObject(value);
lineSeparator(0, index !== array.length - 1);
});
asText += ']';
} else if (obj === null) {
asText +='null';
//undefined
} else if (obj === void(0)) {
asText +='void(0)';
//Special cases for Number
} else if (Number.isNaN(obj)) {
asText +='Number.NaN';
} else if (obj === 1/0) {
asText +='1/0';
} else if (obj === 1/-0) {
asText +='1/-0';
//function
} else if (obj instanceof RegExp || typeof obj === 'function') {
asText += obj.toString();
} else if (obj instanceof Date) {
asText += 'new Date("' + obj.toJSON() + '")';
} else if (typeof obj === 'object') {
asText += '{';
lineSeparator(1);
Object.keys(obj).forEach(function(prop, index, array) {
asText += JSON.stringify(prop) + ': ';
recurseObject(obj[prop]);
lineSeparator(0, index !== array.length - 1);
});
asText += '}';
} else if (['boolean', 'number', 'string'].indexOf(typeof obj) > -1) {
asText += JSON.stringify(obj);
} else {
console.log('Didn\'t handle: typeof obj:', typeof obj, ':: obj:', obj);
}
}
recurseObject(args);
return asText;
}
var newScript = document.createElement('script');
if(typeof id === 'string' && id) {
newScript.id = id;
}
var args = [];
//using .slice(), or other Array methods, on arguments prevents optimization
for(var index=3;index<arguments.length;index++){
args.push(arguments[index]);
}
newScript.textContent = '(' + functionToRunInPage.toString() + ').apply(null,'
+ convertToText(args) + ");";
(document.head || document.documentElement).appendChild(newScript);
if(!leaveInPage) {
//Synchronous scripts are executed immediately and can be immediately removed.
//Scripts with asynchronous functionality of any type must remain in the page
// until complete.
document.head.removeChild(newScript);
}
return newScript;
};
答案 1 :(得分：0)
我今天遇到了一个类似的问题，我的 webextension 必须调用一个只能从特定网页上下文访问的 javascript 函数，我有点恼火，因为我应该执行所有脚本注入和 json 序列化和什么的。但实际上有一个非常简单的解决方案：
window.eval(`updTask(${id})`)
eval 将在页面上下文而不是内容脚本中执行您传递给它的任何代码。
是的，我知道 eval 是邪恶的，但在这种情况下它确实有道理，因为我想做的事情（在网页的上下文中执行任意代码）是邪恶的定义。这就像用正则表达式解析 HTML；一旦你到了那个时候，你就被污染了。此外，您终于摆脱了编写被认为合法的代码的负担。所以让我们拥抱 eval，就这一次 ;)