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:149Please respect copyright.ＰＥＮＡＮＡwdwoq1CLyR
---read whole file content into array buffer---149Please respect copyright.ＰＥＮＡＮＡWUXAa2QybL
let file=input.files[0]; const reader = new FileReader(); 149Please respect copyright.ＰＥＮＡＮＡVtN49xIlFD
reader.onload = () => 149Please respect copyright.ＰＥＮＡＮＡ45ro8ofTKX
{149Please respect copyright.ＰＥＮＡＮＡezGtbTV9wU
let content_whole = new Uint8Array(reader.result);149Please respect copyright.ＰＥＮＡＮＡUualyp1dG7
}149Please respect copyright.ＰＥＮＡＮＡLrWLIDv1ZS
reader.readAsArrayBuffer(file);149Please respect copyright.ＰＥＮＡＮＡ6kbRRaAkxD
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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:149Please respect copyright.ＰＥＮＡＮＡmGKROZGLr3
---read part of file content into array buffer---149Please respect copyright.ＰＥＮＡＮＡfYkd8hwU2m
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 149Please respect copyright.ＰＥＮＡＮＡPUsGV4gUho
reader.onload = () => 149Please respect copyright.ＰＥＮＡＮＡ3RGSo7gsD6
{149Please respect copyright.ＰＥＮＡＮＡSlyPW5WwJR
let content_part = new Uint8Array(reader.result);149Please respect copyright.ＰＥＮＡＮＡOsx0zilNfF
}149Please respect copyright.ＰＥＮＡＮＡkyVxCN9Id3
reader.readAsArrayBuffer(file.slice(start,end));149Please respect copyright.ＰＥＮＡＮＡqzxfWzpP3f
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149Please respect copyright.ＰＥＮＡＮＡD1VvAy7H8n
Section X. Thanks149Please respect copyright.ＰＥＮＡＮＡ03f9dSrt2t
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]149Please respect copyright.ＰＥＮＡＮＡG0PwKOQXGu
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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