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:63Please respect copyright.ＰＥＮＡＮＡWd1sinVpQ8
---read whole file content into array buffer---63Please respect copyright.ＰＥＮＡＮＡFw2W9qtCHF
let file=input.files[0]; const reader = new FileReader(); 63Please respect copyright.ＰＥＮＡＮＡyxB8B3QYGo
reader.onload = () => 63Please respect copyright.ＰＥＮＡＮＡuGw9aHrvuV
{63Please respect copyright.ＰＥＮＡＮＡnVBZfUlkFn
let content_whole = new Uint8Array(reader.result);63Please respect copyright.ＰＥＮＡＮＡ1yfFXU3ve2
}63Please respect copyright.ＰＥＮＡＮＡsdfWzvB1v6
reader.readAsArrayBuffer(file);63Please respect copyright.ＰＥＮＡＮＡvZJZ2uPVW7
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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:63Please respect copyright.ＰＥＮＡＮＡkRo1lKEE2f
---read part of file content into array buffer---63Please respect copyright.ＰＥＮＡＮＡmwTthqPoA2
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 63Please respect copyright.ＰＥＮＡＮＡE0WryPEqpQ
reader.onload = () => 63Please respect copyright.ＰＥＮＡＮＡbiyJZf60WD
{63Please respect copyright.ＰＥＮＡＮＡMr4pM6zh7d
let content_part = new Uint8Array(reader.result);63Please respect copyright.ＰＥＮＡＮＡD3RC7UquFs
}63Please respect copyright.ＰＥＮＡＮＡJG1F9X6rla
reader.readAsArrayBuffer(file.slice(start,end));63Please respect copyright.ＰＥＮＡＮＡxmJmSBvXsA
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63Please respect copyright.ＰＥＮＡＮＡGlXrIqTZmA
Section X. Thanks63Please respect copyright.ＰＥＮＡＮＡ0MiizaUJV5
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]63Please respect copyright.ＰＥＮＡＮＡ0TJr9jaSPy
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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