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:84Please respect copyright.ＰＥＮＡＮＡy07jLosj0G
---read whole file content into array buffer---84Please respect copyright.ＰＥＮＡＮＡcJ6Zf2hoJp
let file=input.files[0]; const reader = new FileReader(); 84Please respect copyright.ＰＥＮＡＮＡFBFgacQHxf
reader.onload = () => 84Please respect copyright.ＰＥＮＡＮＡigJ8RZcD4D
{84Please respect copyright.ＰＥＮＡＮＡMaGHkZ7WdS
let content_whole = new Uint8Array(reader.result);84Please respect copyright.ＰＥＮＡＮＡcKw2HQEtnX
}84Please respect copyright.ＰＥＮＡＮＡiadbqHZchq
reader.readAsArrayBuffer(file);84Please respect copyright.ＰＥＮＡＮＡVIJrPDxgxF
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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:84Please respect copyright.ＰＥＮＡＮＡYcRCUIVtAQ
---read part of file content into array buffer---84Please respect copyright.ＰＥＮＡＮＡRyanILI7zD
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 84Please respect copyright.ＰＥＮＡＮＡLK89XJJfUv
reader.onload = () => 84Please respect copyright.ＰＥＮＡＮＡrwkSaYVCeg
{84Please respect copyright.ＰＥＮＡＮＡTtsjhODUyA
let content_part = new Uint8Array(reader.result);84Please respect copyright.ＰＥＮＡＮＡvRXSh2sZfO
}84Please respect copyright.ＰＥＮＡＮＡ3w8vIyJ8Dh
reader.readAsArrayBuffer(file.slice(start,end));84Please respect copyright.ＰＥＮＡＮＡPF0AhSuRGS
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84Please respect copyright.ＰＥＮＡＮＡUGhtOUnHCR
Section X. Thanks84Please respect copyright.ＰＥＮＡＮＡqy0tUXFlW7
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]84Please respect copyright.ＰＥＮＡＮＡ99aooHmDTN
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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