Question

我无法从后台脚本中获取内容脚本请求值。

content_script.js
=================
var elements = undefined
var properties = undefined
var targets = undefined
chrome.extension.sendRequest({greeting: "elements"}, function(response) {
    elements = response.input;
});
if (elements == undefined){
    var elements = ["a","img"];
}else{
    elements = elements.split(',');
}
chrome.extension.sendRequest({greeting: "properties"}, function(response) {
    properties = response.input;
});
if (properties == undefined){
    var properties = ["alt","id","class"];
}else{
    properties = properties.split(',');
}
chrome.extension.sendRequest({greeting: "targets"}, function(response) {
    targets = response.input;
});
if (targets == undefined){
    var targets = ["onclick","href"];
}else{
    targets = targets.split(',');
}...
...More code and references to elements following...

上述代码仅在代码中断（即等待）之前有效，然后再执行与上述值相关的任何操作，我想我可以做一些事情但我宁愿使用更高效的解决方案可能的。

（供参考:)

background.js
=============
chrome.extension.onRequest.addListener(
function(request, sender, sendResponse) {
    switch (request.greeting){
        case "elements":
                var elements = localStorage["elements"];
                sendResponse({input: elements});
                break;
        case "properties":
                var properties = localStorage["properties"];
                sendResponse({input: properties});
                break;
        case "targets":
                var targets = localStorage["targets"];
                sendResponse({input: targets});
                break;
        }
  });

我已经在这里工作了3个小时（仍在学习我正在用JS做什么）

Answer 1

嗯，你不能这样做：

chrome.extension.sendRequest({greeting: "properties"}, function(response) {
    properties = response.input;
});
if (properties == undefined){ // always undefined
    var properties = ["alt","id","class"];
}else{
    properties = properties.split(',');
}

sendRequest是异步的。

检查undefined的正确方法是：

if (typeof properties == "undefined")

如果您需要所有这些内容，只需提出1个请求并在回调中执行所有操作：

chrome.extension.sendRequest({greeting: "all"}, function(response) {
    if (response.elements === null) {
        var elements = ["a","img"];
    } else {
        var elements = response.elements.split(',');
    }

    if (response.properties === null) {
        var properties = ["alt","id","class"];
    } else {
        var properties = response.properties.split(',');
    }

    if (response.targets === null) {
        var targets = ["onclick","href"];
    } else {
        var targets = response.targets.split(',');
    }
});

在后台：

chrome.extension.onRequest.addListener(function(request, sender, sendResponse) {
    switch (request.greeting){
        case "all":
            sendResponse({
                elements: localStorage.getItem("targets"),
                properties: localStorage.getItem("properties"),
                targets: localStorage.getItem("targets")
            });
            break;
    }
});

Chrome扩展程序 - sendRequest很慢

1 个答案: