Javascript 如何基于来自本地存储的另一个数据响应延迟XMLHttpRequest
在上面的代码中,我试图从本地存储中获取一些参数到变量Javascript 如何基于来自本地存储的另一个数据响应延迟XMLHttpRequest,javascript,google-chrome,google-chrome-extension,xmlhttprequest,local-storage,Javascript,Google Chrome,Google Chrome Extension,Xmlhttprequest,Local Storage,在上面的代码中,我试图从本地存储中获取一些参数到变量ppsParams,但我只想在本地存储请求失败时向CLOUD\u服务器发送请求,目前这两个请求都在执行中,因此,我如何延迟XMLHttpRequest。看起来像是chrome.storage.local.get是异步的,所以移动XMLHttpRequest代码如下所示 //function to download pps_compress.txt from cloud server for global parameter set PPs fu
ppsParams
,但我只想在本地存储请求失败时向CLOUD\u服务器发送请求,目前这两个请求都在执行中,因此,我如何延迟XMLHttpRequest。看起来像是chrome.storage.local.get
是异步的,所以移动XMLHttpRequest代码如下所示
//function to download pps_compress.txt from cloud server for global parameter set PPs
function get_pps_params()
{
chrome.storage.local.get(['ppsParams'], function(result) {
if (typeof(result) !== "undefined" && result != null){
ppsParams = _base64ToArrayBuffer(result.ppsParams);
console.log(ppsParams);
dfd_pps.resolve();
return;
}
});
if(ppsParams == null)
{
var oReq = new XMLHttpRequest();
oReq.open("GET", CLOUD_SERVER + 'get_pps_params', true);
oReq.responseType = "arraybuffer";
oReq.onload = function (oEvent) {
console.log("Got pps params compressed!");
ppsParams = oReq.response; // Note: not oReq.responseText
chrome.storage.local.set({ppsParams: _arrayBufferToBase64(ppsParams)});
dfd_pps.resolve();
};
oReq.send();
}
}
谢谢,这是回调方法,在执行另一段代码之前,没有其他方法等待函数完成吗?您可以使用Promissions-,但对于这个简单的情况来说,这太过分了
function get_pps_params()
{
chrome.storage.local.get(['ppsParams'], function(result) {
if (typeof(result) !== "undefined" && result != null){
ppsParams = _base64ToArrayBuffer(result.ppsParams);
console.log(ppsParams);
dfd_pps.resolve();
}
if(ppsParams == null)
{
var oReq = new XMLHttpRequest();
oReq.open("GET", CLOUD_SERVER + 'get_pps_params', true);
oReq.responseType = "arraybuffer";
oReq.onload = function (oEvent) {
console.log("Got pps params compressed!");
ppsParams = oReq.response; // Note: not oReq.responseText
chrome.storage.local.set({ppsParams: _arrayBufferToBase64(ppsParams)});
dfd_pps.resolve();
};
oReq.send();
}
return;
});
}