如何将价值从popup.js传递到background.js

Question

I hope to deliver the value from popup.js to background.js so that I can open the website as what i expect. I use the localStorage variable as my json's value. But when found that the value I have delieverd to background.js in the argument input of the function openTab(input) is always the string "localStorage.input" itself. How can I solve it?

popup.js

window.onload=function()
{
    localStorage.input=document.getElementById("search").value；

    document.getElementById("submit").onclick=function()
    {
        chrome.extension.sendMessage({command:"start",input:localStorage.input});
    }
}

background.js

chrome.runtime.onMessage.addListener(
    function(request,sender,sendResponse)
    {
        switch(request.command)
        {
            case "start":
                openTab(request.input);
                break;
        }

        return true;
    }
);

var openTab=function(input)
{
    chrome.windows.create
    (
        {
            url:"http://www.baidu.com/s?wd="+input,
        }

    );
};

Answer 1

try this out

var lStore = localStorage.input || '';
window.onload=function()
{
    var search = document.getElementById("search");
    search.value = lStore

    document.getElementById("submit").onclick=function()
    {
        // var input = search.value; //try this as well
        var input = lStore;
        chrome.extension.sendMessage({command:"start",input:input});
    }
}