i有以下JavaScript代码,以在Node.js中运行:
const fs = require("fs");
const path = require("path");
var copy = function(paramSource, paramDestination, paramCallback) {
if (fs.existsSync(paramDestination)) {
return paramCallback("Destination Exists"); //TODO make formal error code
} else {
fs.lstat(paramSource, function(error, sourceStats) {
if (error) {
return paramCallback(error);
} else {
if (sourceStats.isDirectory()) {
fs.readdir(paramSource, function(error, sourceContents) {
if (error) {
return paramCallback(error);
} else {
fs.mkdir(paramDestination, sourceStats.mode, function(error) {
if (error) {
paramCallback(error);
} else {
if (sourceContents.length > 0) {
sourceContents.forEach(function(sourceChild) {
copy(path.join(paramSource, sourceChild), path.join(paramDestination, sourceChild), paramCallback);
});
}
return paramCallback(null, paramDestination);
}
});
}
});
} else {
var sourceFile = fs.createReadStream(paramSource);
var destinationFile = fs.createWriteStream(paramDestination); //TODO permissions
sourceFile.on("error", function(error) {
return paramCallback(error);
});
destinationFile.on("error", function(error) {
return paramCallback(error);
});
sourceFile.on("close", function() {
//return paramCallback(null, paramSource);
});
destinationFile.on("close", function() {
return paramCallback(null, paramDestination);
});
sourceFile.pipe(destinationFile);
}
}
});
}
};
var entities = 0;
copy("/home/fatalkeystroke/testing/directory_01", "/home/fatalkeystroke/testing/directory_01_copy", function(error, name) {
if (error) {
console.log(error);
} else {
console.log(name);
entities++;
}
});
console.log("Copied " + entities + " entities.");
console.log("Program Done.");
这是我正在处理的应用程序中的测试。我想保持copy((函数的异步性质,但是我也希望一种方法来知道何时完成完整副本(因为与entities
相关的代码暗示(。原因是因为我希望能够分辨出何时完成,但也实现了进度跟踪功能。
是否有一种方法可以同步等待JavaScript中的递归异步功能?
这可以使用顺序执行器nsynjs完成。您的代码将如下转换:
var copy = function (src,dst) {
if(nsynFs.lstat(nsynjsCtx, src).data.isDirectory()) {
var files = nsynFs.readdir(nsynjsCtx, src).data;
nsynFs.mkdir(nsynjsCtx,dst);
for(var i=0; i<files.length; i++) {
var f=files[i];
console.log(f);
copy(src+"/"+f, dst+"/"+f);
}
}
else { // is File
var input = nsynFs.open(nsynjsCtx,src,'r').data;
var output = nsynFs.open(nsynjsCtx,dst,'w').data;
var buf = Buffer.alloc(4096);
while(true) {
var readCnt = nsynFs.read(nsynjsCtx,input,buf,0,4096,null).data;
if(!readCnt)
break;
nsynFs.write(nsynjsCtx,output,buf,0,readCnt,null);
}
nsynFs.close(nsynjsCtx,input);
nsynFs.close(nsynjsCtx,output);
}
};
copy("test1","test2");
请在此处查看完整的示例:https://github.com/amaksr/nsynjs/blob/master/master/examples/node-copy-files/index.js