[英]HTML5 ondrop event returns before zip.js can finish operations
我的问题的关键在于我需要异步使用datatransferitemlist,这与规范中描述的功能不一致,即事件结束后您将被锁定在dataTransfer.items集合之外。
https://bugs.chromium.org/p/chromium/issues/detail?id=137231 http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#drag-data -商店
案件罪犯如下。 更详细地描述了我的问题和下面的想法。
drophandler: function(event) {
event.stopPropagation();
event.preventDefault();
event.dataTransfer.dropEffect = 'copy';
zip.workerScriptsPath = "../bower_components/zip.js/WebContent/";
zip.useWebWorkers = false; // Disabled because it just makes life more complicated
// Check if files contains just a zip
if (event.dataTransfer.files[0].name.match(/(?:\.([^.]+))?$/) == 'zip') {
var reader = new FileReader();
that = this;
reader.onload = function(e) {
that.fire('zipuploaded', e.target.result.split(',')[1]);
}
reader.readAsDataURL(event.dataTransfer.files[0]);
// Rev up that in browser zipping
} else {
var that = this;
var items = event.dataTransfer.items;
// Async operation, execution falls through from here
zip.createWriter(new zip.Data64URIWriter(), function(writer) {
(function traverse(list, path, i, depth) {
return new Promise(function(resolve, reject) {
var item;
if (depth == 0) {
if (i == list.length) {
writer.close(function(uri) {
that.fire('zipuploaded', uri.split(',')[1]); // Just the base64, please
fulfill(1);
return;
});
} else {
console.log(i);
console.log(list);
var item = list[i].webkitGetAsEntry();
}
} else {
if (i == list.length) {
resolve(0);
return;
} else {
item = list[i];
}
}
if (item.isFile) {
item.file(function(file) {
// Zipping operations done asynchronously, it'll fail by roughly the second operation
writer.add(path + file.name, zip.BlobReader(file), function() {
traverse(list, path, i + 1, depth).then(resolve(0)); // Next item
});
});
} else if (item.isDirectory) {
var dirReader = item.createDirReader();
dirReader.readEntries(function(entries) {
// Operate on child folder then the next item at this level
traverse(entries, path + item.name + "/", 0, depth + 1).then(function() {
traverse(list, path, i + 1, depth).then(resolve(0));
});
});
}
});
})(items, "", 0, 0); // Begin with datatransferitemlist, 0th element, depth 0
});
this.$.uploadarea.classList.remove('highlightdrag');
}
// When we exit it kills the event.dataTransfer.items
},
我使用的是与HTML5 DnD API异步的zip.js。 ondrop事件在异步zip.createWriter / writer.add操作完成之前结束。 我可以想到解决这个问题的四种方法,虽然我不知道如何实现它们并且想要一些建议。
HTML5 DnD按预期工作。 问题是,当添加多个文件时,如果你在上一次完成之前添加一个文件, zip.js
会默默地中断。 这可以通过writer.add
调用writer.add
来解决。
该代码段可能不起作用,请参阅此笔 。
这个例子展示了已删除文件的结构,然后将其添加到zip 中 。
function mes(it) { const m = document.querySelector('#mes') return m.textContent = it + '\\n' + m.textContent } function read(items) { return Promise.all(items.map(item => { if (item.isFile) return [item] return new Promise(resolve => item.createReader().readEntries(resolve)) .then(entries => { entries.forEach(it => it.path = item.path + '/' + it.name) return read(entries) }) })).then(entries => entries.reduce((a, b) => a.concat(b))) } function handleResult(blob){ const res = document.querySelector('#result') res.download = 'files.zip' res.href = window.URL.createObjectURL(blob) res.textContent = 'download zipped file' } function handleItems(items){ mes(items.length) items.forEach(item => item.path = item.name) const initZip = new Promise(resolve => zip.createWriter(new zip.BlobWriter, resolve) ) const getFiles = read(items).then(entries => { return Promise.all(entries.map(entry => new Promise(resolve => entry.file(file => { file.path = entry.path resolve(file) }) ) )) }) return Promise.all([getFiles, initZip]).then(([files, writer]) => files.reduce((current, next) => current.then(() => new Promise(resolve => { mes(next.path) writer.add(next.path, new zip.BlobReader(next), resolve) }) ) , Promise.resolve()) .then(() => writer.close(handleResult)) ) } zip.useWebWorkers = false const drop = document.querySelector('#drop'); ['dragover', 'drop'].forEach(name => drop.addEventListener(name, ev => ev.preventDefault()) ) drop.addEventListener('drop', ev => { const items = [].slice.call(ev.dataTransfer.items) .map(item => item.webkitGetAsEntry()) return handleItems(items) })
html, body, #drop { height: 100%; width: 100%; }
<script src="http://gildas-lormeau.github.io/zip.js/demos/zip.js"></script> <script src="http://gildas-lormeau.github.io/zip.js/demos/deflate.js"></script> <div id="drop"> Drop here! <br> <a id="result"></a> </div> <pre id="mes"></pre>
jszip比这容易得多,你可能想尝试一下。
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