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:152Please respect copyright.ＰＥＮＡＮＡr9gO7qivWQ
---read whole file content into array buffer---152Please respect copyright.ＰＥＮＡＮＡJCaiPWGHNC
let file=input.files[0]; const reader = new FileReader(); 152Please respect copyright.ＰＥＮＡＮＡxOzmXolczZ
reader.onload = () => 152Please respect copyright.ＰＥＮＡＮＡs9YFAg5L4K
{152Please respect copyright.ＰＥＮＡＮＡcIN9ufST5C
let content_whole = new Uint8Array(reader.result);152Please respect copyright.ＰＥＮＡＮＡg5DpCUq9qr
}152Please respect copyright.ＰＥＮＡＮＡ6M15h5IQMz
reader.readAsArrayBuffer(file);152Please respect copyright.ＰＥＮＡＮＡYvnAcTLVQV
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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:152Please respect copyright.ＰＥＮＡＮＡYuqDmpbtpb
---read part of file content into array buffer---152Please respect copyright.ＰＥＮＡＮＡKynyqm75Wo
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 152Please respect copyright.ＰＥＮＡＮＡRvVoqD364O
reader.onload = () => 152Please respect copyright.ＰＥＮＡＮＡAqHBzqwTJ7
{152Please respect copyright.ＰＥＮＡＮＡkb0hMT9CgF
let content_part = new Uint8Array(reader.result);152Please respect copyright.ＰＥＮＡＮＡ4B58KfNVyE
}152Please respect copyright.ＰＥＮＡＮＡda4Q0N38vM
reader.readAsArrayBuffer(file.slice(start,end));152Please respect copyright.ＰＥＮＡＮＡZsbpjugp5h
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152Please respect copyright.ＰＥＮＡＮＡQa45pscZt3
Section X. Thanks152Please respect copyright.ＰＥＮＡＮＡCAf6EDezZS
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]152Please respect copyright.ＰＥＮＡＮＡmUB7jcolk7
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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