本文描述了使用javascript读取用户通过Input控件选择的文件的内容的方法和注意事项。后面用英文写，但我的英文不太好，如有错误之处，希望大家帮我纠正，我的联系方式在后面。
When user select a file by <input type=file>, its content can be read by javascript like this:132Please respect copyright.ＰＥＮＡＮＡdYvRfWUQ8t
---read whole file content into array buffer---132Please respect copyright.ＰＥＮＡＮＡPPnwoY94bE
let file=input.files[0]; const reader = new FileReader(); 132Please respect copyright.ＰＥＮＡＮＡ97vdYyosT3
reader.onload = () => 132Please respect copyright.ＰＥＮＡＮＡgfzLNu6KbK
{132Please respect copyright.ＰＥＮＡＮＡ2atrVj67uN
let content_whole = new Uint8Array(reader.result);132Please respect copyright.ＰＥＮＡＮＡDcs7A4CjCZ
}132Please respect copyright.ＰＥＮＡＮＡEUW1jgOmh8
reader.readAsArrayBuffer(file);132Please respect copyright.ＰＥＮＡＮＡhsDhfcpYy5
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If the file size is too large, the browser may crash as the whole file content are loaded into memory by array buffer. In order to avoid it, we can just read a part of the file like this:132Please respect copyright.ＰＥＮＡＮＡTAdDD12Og2
---read part of file content into array buffer---132Please respect copyright.ＰＥＮＡＮＡ3Jb3CfmH2Y
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 132Please respect copyright.ＰＥＮＡＮＡgNm4GGpNgm
reader.onload = () => 132Please respect copyright.ＰＥＮＡＮＡKNo3q82Xve
{132Please respect copyright.ＰＥＮＡＮＡpJybgw2A1Z
let content_part = new Uint8Array(reader.result);132Please respect copyright.ＰＥＮＡＮＡZ88oaQOMa3
}132Please respect copyright.ＰＥＮＡＮＡmf8O8Fn4U5
reader.readAsArrayBuffer(file.slice(start,end));132Please respect copyright.ＰＥＮＡＮＡZI1oKjXim0
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132Please respect copyright.ＰＥＮＡＮＡ1vvyMHNXCM
Section X. Thanks132Please respect copyright.ＰＥＮＡＮＡCRgrQeddd1
https://segmentfault.com/a/1190000022113605
Section Y. Contacts Me
If you found any errors or have any suggestions for this article, please let me know, my wechat: si_jinmin, my email: [email protected]132Please respect copyright.ＰＥＮＡＮＡEE1SbMdQMZ
如果您发现本文有任何错误，或者对本文有好的建议，欢迎与我联系探讨，我的微信: si_jinmin, 我的email: [email protected]
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