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:53Please respect copyright.ＰＥＮＡＮＡRBUYAAu1P6
---read whole file content into array buffer---53Please respect copyright.ＰＥＮＡＮＡZfVYLnWcvr
let file=input.files[0]; const reader = new FileReader(); 53Please respect copyright.ＰＥＮＡＮＡhdItmhy6Dm
reader.onload = () => 53Please respect copyright.ＰＥＮＡＮＡv035ozyc0h
{53Please respect copyright.ＰＥＮＡＮＡN8yB3t5ejl
let content_whole = new Uint8Array(reader.result);53Please respect copyright.ＰＥＮＡＮＡgRwuoRnwIV
}53Please respect copyright.ＰＥＮＡＮＡQZDNdd6k5q
reader.readAsArrayBuffer(file);53Please respect copyright.ＰＥＮＡＮＡo2WuJpSR08
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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:53Please respect copyright.ＰＥＮＡＮＡRy03rfJTaI
---read part of file content into array buffer---53Please respect copyright.ＰＥＮＡＮＡfv55nc8MlL
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 53Please respect copyright.ＰＥＮＡＮＡV8sIUgQkLn
reader.onload = () => 53Please respect copyright.ＰＥＮＡＮＡqdUqGPq5o8
{53Please respect copyright.ＰＥＮＡＮＡr6vxs6IWk3
let content_part = new Uint8Array(reader.result);53Please respect copyright.ＰＥＮＡＮＡIzN59kYF6J
}53Please respect copyright.ＰＥＮＡＮＡyV3cvwrQf9
reader.readAsArrayBuffer(file.slice(start,end));53Please respect copyright.ＰＥＮＡＮＡCchtiXP9mI
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53Please respect copyright.ＰＥＮＡＮＡYBMuVjM8ZY
Section X. Thanks53Please respect copyright.ＰＥＮＡＮＡruVr9BOj3f
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]53Please respect copyright.ＰＥＮＡＮＡ4JicNUM4zG
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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