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:104Please respect copyright.ＰＥＮＡＮＡ4zhPOncs68
---read whole file content into array buffer---104Please respect copyright.ＰＥＮＡＮＡ3ZlQAlAKBD
let file=input.files[0]; const reader = new FileReader(); 104Please respect copyright.ＰＥＮＡＮＡBSEtpKyHNB
reader.onload = () => 104Please respect copyright.ＰＥＮＡＮＡZ9ZTl9lH0D
{104Please respect copyright.ＰＥＮＡＮＡ9HwWoarIz6
let content_whole = new Uint8Array(reader.result);104Please respect copyright.ＰＥＮＡＮＡ246CQph9VJ
}104Please respect copyright.ＰＥＮＡＮＡ4feZ0BMftC
reader.readAsArrayBuffer(file);104Please respect copyright.ＰＥＮＡＮＡ4JJRZrR468
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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:104Please respect copyright.ＰＥＮＡＮＡM2h7ZZKGhy
---read part of file content into array buffer---104Please respect copyright.ＰＥＮＡＮＡ1hQ5P5TA2G
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 104Please respect copyright.ＰＥＮＡＮＡtj2kyTREhw
reader.onload = () => 104Please respect copyright.ＰＥＮＡＮＡSyvTYVlobl
{104Please respect copyright.ＰＥＮＡＮＡr5GgZCYHzb
let content_part = new Uint8Array(reader.result);104Please respect copyright.ＰＥＮＡＮＡawruVI9W0E
}104Please respect copyright.ＰＥＮＡＮＡ8vhrzyGF6p
reader.readAsArrayBuffer(file.slice(start,end));104Please respect copyright.ＰＥＮＡＮＡYu8m4qBnB9
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104Please respect copyright.ＰＥＮＡＮＡhw3V5JBBWB
Section X. Thanks104Please respect copyright.ＰＥＮＡＮＡfJL4YgHhfU
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]104Please respect copyright.ＰＥＮＡＮＡsFGE5umfCP
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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