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:154Please respect copyright.ＰＥＮＡＮＡXvLjMvD46t
---read whole file content into array buffer---154Please respect copyright.ＰＥＮＡＮＡoPKitp3ZGN
let file=input.files[0]; const reader = new FileReader(); 154Please respect copyright.ＰＥＮＡＮＡw2zgYWPLuX
reader.onload = () => 154Please respect copyright.ＰＥＮＡＮＡhEsiuuUJjC
{154Please respect copyright.ＰＥＮＡＮＡiOmw6HO6z3
let content_whole = new Uint8Array(reader.result);154Please respect copyright.ＰＥＮＡＮＡEBWTGZKC68
}154Please respect copyright.ＰＥＮＡＮＡgIDDozD1Wu
reader.readAsArrayBuffer(file);154Please respect copyright.ＰＥＮＡＮＡjPjbaZnAP4
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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:154Please respect copyright.ＰＥＮＡＮＡEU98LH7zJk
---read part of file content into array buffer---154Please respect copyright.ＰＥＮＡＮＡxEEqXi585T
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 154Please respect copyright.ＰＥＮＡＮＡ8UtLotZpCb
reader.onload = () => 154Please respect copyright.ＰＥＮＡＮＡrtDMQu8LvD
{154Please respect copyright.ＰＥＮＡＮＡpDVIC0aYGx
let content_part = new Uint8Array(reader.result);154Please respect copyright.ＰＥＮＡＮＡ2N3fNYXOOQ
}154Please respect copyright.ＰＥＮＡＮＡvQzvjk9IVm
reader.readAsArrayBuffer(file.slice(start,end));154Please respect copyright.ＰＥＮＡＮＡqbUu94pM6J
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154Please respect copyright.ＰＥＮＡＮＡyiolb2Gwap
Section X. Thanks154Please respect copyright.ＰＥＮＡＮＡyGt9880TXg
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]154Please respect copyright.ＰＥＮＡＮＡzlHGcS7wQz
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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