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:128Please respect copyright.ＰＥＮＡＮＡ3e9TpU5kUh
---read whole file content into array buffer---128Please respect copyright.ＰＥＮＡＮＡ3WiWaCHn07
let file=input.files[0]; const reader = new FileReader(); 128Please respect copyright.ＰＥＮＡＮＡ5Ad4DIWDlJ
reader.onload = () => 128Please respect copyright.ＰＥＮＡＮＡjIh6IZL4Tb
{128Please respect copyright.ＰＥＮＡＮＡYc1xKjK3g9
let content_whole = new Uint8Array(reader.result);128Please respect copyright.ＰＥＮＡＮＡvEANHtd2WD
}128Please respect copyright.ＰＥＮＡＮＡVhKokZCMmM
reader.readAsArrayBuffer(file);128Please respect copyright.ＰＥＮＡＮＡFTA6AzXK1r
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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:128Please respect copyright.ＰＥＮＡＮＡOjtCl9WT09
---read part of file content into array buffer---128Please respect copyright.ＰＥＮＡＮＡlOKaSc5DAN
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 128Please respect copyright.ＰＥＮＡＮＡ1qdD6JBVPC
reader.onload = () => 128Please respect copyright.ＰＥＮＡＮＡL5b4MKnp1Z
{128Please respect copyright.ＰＥＮＡＮＡxKVCfxjQEp
let content_part = new Uint8Array(reader.result);128Please respect copyright.ＰＥＮＡＮＡfTY1lX5xqG
}128Please respect copyright.ＰＥＮＡＮＡKBB3oPUBZs
reader.readAsArrayBuffer(file.slice(start,end));128Please respect copyright.ＰＥＮＡＮＡkxnWnO5MWT
-----------------------------------------------
128Please respect copyright.ＰＥＮＡＮＡpyGoDldh62
Section X. Thanks128Please respect copyright.ＰＥＮＡＮＡ13FkwUtMTs
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]128Please respect copyright.ＰＥＮＡＮＡb4uosNzQlK
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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