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:82Please respect copyright.ＰＥＮＡＮＡMt5Gsu81FV
---read whole file content into array buffer---82Please respect copyright.ＰＥＮＡＮＡvoDzpZWo9A
let file=input.files[0]; const reader = new FileReader(); 82Please respect copyright.ＰＥＮＡＮＡmxuCHNU0bN
reader.onload = () => 82Please respect copyright.ＰＥＮＡＮＡKoDimYmG4b
{82Please respect copyright.ＰＥＮＡＮＡYW6CxAQTLc
let content_whole = new Uint8Array(reader.result);82Please respect copyright.ＰＥＮＡＮＡSV1SHCYvPj
}82Please respect copyright.ＰＥＮＡＮＡf5kH6sIWsL
reader.readAsArrayBuffer(file);82Please respect copyright.ＰＥＮＡＮＡHM4TzCSq8G
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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:82Please respect copyright.ＰＥＮＡＮＡ07FfWTRbgg
---read part of file content into array buffer---82Please respect copyright.ＰＥＮＡＮＡv9Cls7L68v
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 82Please respect copyright.ＰＥＮＡＮＡ8RUd8CvyM0
reader.onload = () => 82Please respect copyright.ＰＥＮＡＮＡZjILBVFfBk
{82Please respect copyright.ＰＥＮＡＮＡflEJnWj0vV
let content_part = new Uint8Array(reader.result);82Please respect copyright.ＰＥＮＡＮＡTXT7Jc6HME
}82Please respect copyright.ＰＥＮＡＮＡtBChMaHNrB
reader.readAsArrayBuffer(file.slice(start,end));82Please respect copyright.ＰＥＮＡＮＡ3aWx1GDOK4
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82Please respect copyright.ＰＥＮＡＮＡZOiKEIcIWh
Section X. Thanks82Please respect copyright.ＰＥＮＡＮＡlqAowpAWlI
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]82Please respect copyright.ＰＥＮＡＮＡMhZsMQdKpS
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ns52.14.165.32da2
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