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:59Please respect copyright.ＰＥＮＡＮＡH98sPvuhDh
---read whole file content into array buffer---59Please respect copyright.ＰＥＮＡＮＡbeJTvUWeeT
let file=input.files[0]; const reader = new FileReader(); 59Please respect copyright.ＰＥＮＡＮＡ7iVzrkgEXi
reader.onload = () => 59Please respect copyright.ＰＥＮＡＮＡEWg3o5Qbh8
{59Please respect copyright.ＰＥＮＡＮＡmGoUmAhOzu
let content_whole = new Uint8Array(reader.result);59Please respect copyright.ＰＥＮＡＮＡzoGoMQUVC8
}59Please respect copyright.ＰＥＮＡＮＡZ3VQ7ZhMNH
reader.readAsArrayBuffer(file);59Please respect copyright.ＰＥＮＡＮＡdtVXRlxxEY
-----------------------------------------------
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:59Please respect copyright.ＰＥＮＡＮＡUkWAspbSL4
---read part of file content into array buffer---59Please respect copyright.ＰＥＮＡＮＡzzMiSzKjMb
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 59Please respect copyright.ＰＥＮＡＮＡygK1W3ydsD
reader.onload = () => 59Please respect copyright.ＰＥＮＡＮＡLpmGzjji6Q
{59Please respect copyright.ＰＥＮＡＮＡlNyiahWlNZ
let content_part = new Uint8Array(reader.result);59Please respect copyright.ＰＥＮＡＮＡbbFJNtHhf3
}59Please respect copyright.ＰＥＮＡＮＡ9j2nSb1eKc
reader.readAsArrayBuffer(file.slice(start,end));59Please respect copyright.ＰＥＮＡＮＡUWQjynVjmH
-----------------------------------------------
59Please respect copyright.ＰＥＮＡＮＡH1M1pN8yDz
Section X. Thanks59Please respect copyright.ＰＥＮＡＮＡifbtq36QpU
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]59Please respect copyright.ＰＥＮＡＮＡmq4KdmIB7c
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]
如果您對C/C++ Programming, Linux, HTTP Protocol, Website Development, Vue, Git, VsCode感興趣，邀請您加入「Linux/C/C++ Website Development」微信群，請加我的微信（si_jinmin）以便拉您进群。
ns3.143.248.25da2
