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:135Please respect copyright.ＰＥＮＡＮＡt6EVh9JkRL
---read whole file content into array buffer---135Please respect copyright.ＰＥＮＡＮＡlKzo18WCkv
let file=input.files[0]; const reader = new FileReader(); 135Please respect copyright.ＰＥＮＡＮＡyYVO9dazjl
reader.onload = () => 135Please respect copyright.ＰＥＮＡＮＡ46HghJZg1V
{135Please respect copyright.ＰＥＮＡＮＡYsxvlcsKa0
let content_whole = new Uint8Array(reader.result);135Please respect copyright.ＰＥＮＡＮＡTxB1ea2DKX
}135Please respect copyright.ＰＥＮＡＮＡCLhJ23jPFj
reader.readAsArrayBuffer(file);135Please respect copyright.ＰＥＮＡＮＡGpoPSpEYXD
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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:135Please respect copyright.ＰＥＮＡＮＡ4U8mpCpdHJ
---read part of file content into array buffer---135Please respect copyright.ＰＥＮＡＮＡcOVGIdrfLa
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 135Please respect copyright.ＰＥＮＡＮＡJLE94JgeC9
reader.onload = () => 135Please respect copyright.ＰＥＮＡＮＡspKkJsaphr
{135Please respect copyright.ＰＥＮＡＮＡKlPl8ohmnU
let content_part = new Uint8Array(reader.result);135Please respect copyright.ＰＥＮＡＮＡl1TwP8nvqe
}135Please respect copyright.ＰＥＮＡＮＡOfejf0AMBJ
reader.readAsArrayBuffer(file.slice(start,end));135Please respect copyright.ＰＥＮＡＮＡrlESTFmhra
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135Please respect copyright.ＰＥＮＡＮＡy3ZTRPieCx
Section X. Thanks135Please respect copyright.ＰＥＮＡＮＡvqjxQULB0e
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]135Please respect copyright.ＰＥＮＡＮＡrAgKhM98AQ
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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ns216.73.216.100da2
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