是否有一种普遍接受的技术可以有效地将JavaScript字符串转换为arraybuffer,反之亦然?具体来说,我希望能够将ArrayBuffer的内容写入localStorage,然后再将其读回来。
当前回答
你可以使用Encoding标准中的TextEncoder和TextDecoder,该标准由stringencoding库填充,用于将字符串转换为ArrayBuffers:
var uint8array = new TextEncoder().encode(string);
var string = new TextDecoder(encoding).decode(uint8array);
其他回答
var decoder = new TextDecoder ();
var string = decoder.decode (arrayBuffer);
参见https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder/decode
尽管Dennis和gengkev使用Blob/FileReader的解决方案有效,但我不建议采用这种方法。这是一种解决简单问题的异步方法,比直接解决方案要慢得多。我在html5rocks上发布了一个更简单(更快)的解决方案: http://updates.html5rocks.com/2012/06/How-to-convert-ArrayBuffer-to-and-from-String
解决方案是:
function ab2str(buf) {
return String.fromCharCode.apply(null, new Uint16Array(buf));
}
function str2ab(str) {
var buf = new ArrayBuffer(str.length*2); // 2 bytes for each char
var bufView = new Uint16Array(buf);
for (var i=0, strLen=str.length; i<strLen; i++) {
bufView[i] = str.charCodeAt(i);
}
return buf;
}
编辑:
Encoding API帮助解决字符串转换问题。请查看Jeff Posnik在Html5Rocks.com上对上述原创文章的回复。
摘录:
Encoding API使原始字节和原生JavaScript字符串之间的转换变得简单,而不考虑需要使用的许多标准编码中的哪一种。
<pre id="results"></pre>
<script>
if ('TextDecoder' in window) {
// The local files to be fetched, mapped to the encoding that they're using.
var filesToEncoding = {
'utf8.bin': 'utf-8',
'utf16le.bin': 'utf-16le',
'macintosh.bin': 'macintosh'
};
Object.keys(filesToEncoding).forEach(function(file) {
fetchAndDecode(file, filesToEncoding[file]);
});
} else {
document.querySelector('#results').textContent = 'Your browser does not support the Encoding API.'
}
// Use XHR to fetch `file` and interpret its contents as being encoded with `encoding`.
function fetchAndDecode(file, encoding) {
var xhr = new XMLHttpRequest();
xhr.open('GET', file);
// Using 'arraybuffer' as the responseType ensures that the raw data is returned,
// rather than letting XMLHttpRequest decode the data first.
xhr.responseType = 'arraybuffer';
xhr.onload = function() {
if (this.status == 200) {
// The decode() method takes a DataView as a parameter, which is a wrapper on top of the ArrayBuffer.
var dataView = new DataView(this.response);
// The TextDecoder interface is documented at http://encoding.spec.whatwg.org/#interface-textdecoder
var decoder = new TextDecoder(encoding);
var decodedString = decoder.decode(dataView);
// Add the decoded file's text to the <pre> element on the page.
document.querySelector('#results').textContent += decodedString + '\n';
} else {
console.error('Error while requesting', file, this);
}
};
xhr.send();
}
</script>
我发现这种方法有问题,主要是因为我试图将输出写入一个文件,而它没有正确编码。由于JS似乎使用UCS-2编码(源,源),我们需要进一步扩展这个解决方案,这是我的增强解决方案,对我来说是有效的。
我对一般文本没有任何困难,但当它变成阿拉伯语或韩语时,输出文件没有所有字符,而是显示错误字符
文件输出: ”、“单位”:“10 K”:“O©iuY喜爱”、“遵循% % {screen_name} {screen_name}”:“U”“O©iu“推特:“¤问题”、“推%{标签}”:“%{标签}’一个¤uEY喜爱”,“推特%{名称}”:“%{名称}U”xA¤uEY喜爱”},柯:{“% {followers_count}的追随者”:“% {followers_count}…X \”,“100 K +”:“100我助教”,“10 K单位”:“我e”,遵循:“\°”,“跟着% {screen_name}”:“% {screen_name}Ø\°X0”,凯西:“œ”,男:“我”,推特:“¸”,“推特%{标签}”:“%{标签}
original: ", " 10 k unit ": "万",follow: "关注"," follow百分之百分之;screen _ name} ": " {screen _ name}先生圆场,tweet: "推特"," tweet百分之百分之{hashtag} ": " {hashtag},推特的"," tweet to百分之百分之{name} ": " {name}先生推到百分之":{},ko " {followers _ count}百分之followers ": " {followers _ count}명의팔로워100 k + ": " 100 ", "만이상"," 10 k unit ": "만단위",follow: "팔로우"," follow百分之百分之{screen _ name} ": " {screen _ name}님팔로우하기",k: "천",米:"백만",tweet: "트윗"," tweet百分之百分之{hashtag} ": " {hashtag}
我从dennis的解决方案和我发现的这个帖子中获取了信息。
这是我的代码:
function encode_utf8(s) {
return unescape(encodeURIComponent(s));
}
function decode_utf8(s) {
return decodeURIComponent(escape(s));
}
function ab2str(buf) {
var s = String.fromCharCode.apply(null, new Uint8Array(buf));
return decode_utf8(decode_utf8(s))
}
function str2ab(str) {
var s = encode_utf8(str)
var buf = new ArrayBuffer(s.length);
var bufView = new Uint8Array(buf);
for (var i=0, strLen=s.length; i<strLen; i++) {
bufView[i] = s.charCodeAt(i);
}
return bufView;
}
这允许我将内容保存到一个文件,而没有编码问题。
How it works: It basically takes the single 8-byte chunks composing a UTF-8 character and saves them as single characters (therefore an UTF-8 character built in this way, could be composed by 1-4 of these characters). UTF-8 encodes characters in a format that variates from 1 to 4 bytes in length. What we do here is encoding the sting in an URI component and then take this component and translate it in the corresponding 8 byte character. In this way we don't lose the information given by UTF8 characters that are more than 1 byte long.
Just
const buffer = thisReturnsBuffers();
const blob = new Blob([buffer], {type: 'text/plain; charset=utf-8'});
blob.text().then(text => console.log(text));
Or
const stringVal = "string here";
const blob = new Blob([stringVal], {type: 'text/plain; charset=utf-8'});
blob.arrayBuffer().then(buffer => console.log(buffer));
你们为什么要把事情搞得这么复杂?
我用了这个,对我很有用。
function arrayBufferToBase64( buffer ) {
var binary = '';
var bytes = new Uint8Array( buffer );
var len = bytes.byteLength;
for (var i = 0; i < len; i++) {
binary += String.fromCharCode( bytes[ i ] );
}
return window.btoa( binary );
}
function base64ToArrayBuffer(base64) {
var binary_string = window.atob(base64);
var len = binary_string.length;
var bytes = new Uint8Array( len );
for (var i = 0; i < len; i++) {
bytes[i] = binary_string.charCodeAt(i);
}
return bytes.buffer;
}
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