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:160Please respect copyright.ＰＥＮＡＮＡEfAkX62a5o
---read whole file content into array buffer---160Please respect copyright.ＰＥＮＡＮＡu8tCYZOMhz
let file=input.files[0]; const reader = new FileReader(); 160Please respect copyright.ＰＥＮＡＮＡPeqw45d4md
reader.onload = () => 160Please respect copyright.ＰＥＮＡＮＡ4x9mpniTKK
{160Please respect copyright.ＰＥＮＡＮＡINGm1NC4rx
let content_whole = new Uint8Array(reader.result);160Please respect copyright.ＰＥＮＡＮＡbu07H39XpF
}160Please respect copyright.ＰＥＮＡＮＡDYwzeXJbpL
reader.readAsArrayBuffer(file);160Please respect copyright.ＰＥＮＡＮＡS3kk9aItwS
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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:160Please respect copyright.ＰＥＮＡＮＡWjDvRKvtx7
---read part of file content into array buffer---160Please respect copyright.ＰＥＮＡＮＡSeWqeozuOQ
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 160Please respect copyright.ＰＥＮＡＮＡYNpjlYQaLV
reader.onload = () => 160Please respect copyright.ＰＥＮＡＮＡDYJsP1mK39
{160Please respect copyright.ＰＥＮＡＮＡGRanaPHhsN
let content_part = new Uint8Array(reader.result);160Please respect copyright.ＰＥＮＡＮＡx8VQhdnRED
}160Please respect copyright.ＰＥＮＡＮＡATgV5YpGd9
reader.readAsArrayBuffer(file.slice(start,end));160Please respect copyright.ＰＥＮＡＮＡ03E2sE7CVG
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160Please respect copyright.ＰＥＮＡＮＡ8Q6QtnsOiA
Section X. Thanks160Please respect copyright.ＰＥＮＡＮＡQo7D9W8hbM
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]160Please respect copyright.ＰＥＮＡＮＡcSdm8nP1ch
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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