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:127Please respect copyright.ＰＥＮＡＮＡ3yThOHAcNP
---read whole file content into array buffer---127Please respect copyright.ＰＥＮＡＮＡSfMyPrTlhO
let file=input.files[0]; const reader = new FileReader(); 127Please respect copyright.ＰＥＮＡＮＡIeyleKIYdZ
reader.onload = () => 127Please respect copyright.ＰＥＮＡＮＡuIQjRwitID
{127Please respect copyright.ＰＥＮＡＮＡMP3ICRjHIN
let content_whole = new Uint8Array(reader.result);127Please respect copyright.ＰＥＮＡＮＡJMBJZuMNoa
}127Please respect copyright.ＰＥＮＡＮＡ1Rg3ZSpFTA
reader.readAsArrayBuffer(file);127Please respect copyright.ＰＥＮＡＮＡf4i3kmyqES
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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:127Please respect copyright.ＰＥＮＡＮＡY1AtQvcisP
---read part of file content into array buffer---127Please respect copyright.ＰＥＮＡＮＡXhHcU4l1K2
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 127Please respect copyright.ＰＥＮＡＮＡ2wODwlxfrE
reader.onload = () => 127Please respect copyright.ＰＥＮＡＮＡd7HTD87iFv
{127Please respect copyright.ＰＥＮＡＮＡGBn85pnLFm
let content_part = new Uint8Array(reader.result);127Please respect copyright.ＰＥＮＡＮＡI0Z9NAMXbz
}127Please respect copyright.ＰＥＮＡＮＡLmlliwBreM
reader.readAsArrayBuffer(file.slice(start,end));127Please respect copyright.ＰＥＮＡＮＡmZJoBTjK9k
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127Please respect copyright.ＰＥＮＡＮＡsSEyVHaBOa
Section X. Thanks127Please respect copyright.ＰＥＮＡＮＡLp8L2ed2Lb
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]127Please respect copyright.ＰＥＮＡＮＡpitAy7a0gA
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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