javascript Node.js：在修改时确定文件大小
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Node.js: Determine file size on modification
提问by hexacyanide
I'm watching a file in Node.js and would like to obtain the size of the file each time it changes. How can this be done with fs.watchFile?
我正在观察 Node.js 中的一个文件，并希望在每次更改时获取该文件的大小。如何做到这一点fs.watchFile？
This is what I'm currently doing:
这就是我目前正在做的事情：
fs.watchFile(file, function(curr, prev) {
// determine file size
});
回答by Vadim Baryshev
var fs = require('fs');
fs.watchFile('some.file', function () {
fs.stat('some.file', function (err, stats) {
console.log(stats.size);
});
});
回答by hexacyanide
I missed that the variables currand prevthat were returned from fs.watchFilewere instances of fs.Stats. This would be the optimal solution:
我错过了变量curr和prev返回的变量fs.watchFile是fs.Stats. 这将是最佳解决方案：
var fs = require('fs');
fs.watchFile('file', function (curr, prev) {
console.log(curr.size);
});
However, as of Node v0.8.0, fs.watchFileno longer uses IOWatcher, and now uses stat polling, which is slow and does not provide realtime updates. This was discussed on GitHub.
但是，从 Node v0.8.0 开始，fs.watchFile不再使用IOWatcher，现在使用 stat 轮询，它很慢并且不提供实时更新。这是在GitHub 上讨论的。
From the Node changelog:
从节点更改日志：
Deprecate iowatcher, fs: fix fs.watchFile() (Ben Noordhuis)
弃用 iowatcher，fs：修复 fs.watchFile() (Ben Noordhuis)
Instead, an alternate solution is now fs.watchand fs.stat:
相反，另一种解决方案是现在fs.watch和fs.stat：
var fs = require('fs');
fs.watch('file', function (curr, prev) {
fs.stat('file', function (err, stats) {
console.log(stats.size);
});
});
回答by Femi
Use fs.statin the callback: watchFilejust lets you know it changed, it doesn't report the change details.
fs.stat在回调中使用：watchFile只是让您知道它已更改，它不会报告更改详细信息。
