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:124Please respect copyright.ＰＥＮＡＮＡ9ZJ39jvMqC
---read whole file content into array buffer---124Please respect copyright.ＰＥＮＡＮＡ60erESBblL
let file=input.files[0]; const reader = new FileReader(); 124Please respect copyright.ＰＥＮＡＮＡKSAd2FN1V7
reader.onload = () => 124Please respect copyright.ＰＥＮＡＮＡXKPxurB9SB
{124Please respect copyright.ＰＥＮＡＮＡ00ah0MYSMN
let content_whole = new Uint8Array(reader.result);124Please respect copyright.ＰＥＮＡＮＡWyB4763his
}124Please respect copyright.ＰＥＮＡＮＡHVZWAmX8gZ
reader.readAsArrayBuffer(file);124Please respect copyright.ＰＥＮＡＮＡ4CyIRXMoT9
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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:124Please respect copyright.ＰＥＮＡＮＡ8617GySYkI
---read part of file content into array buffer---124Please respect copyright.ＰＥＮＡＮＡprolzh5v4i
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 124Please respect copyright.ＰＥＮＡＮＡAw2RrsJq21
reader.onload = () => 124Please respect copyright.ＰＥＮＡＮＡoDuEqAAcP9
{124Please respect copyright.ＰＥＮＡＮＡW9YeHEttC3
let content_part = new Uint8Array(reader.result);124Please respect copyright.ＰＥＮＡＮＡVBVTXBfr6J
}124Please respect copyright.ＰＥＮＡＮＡnLn6pXGFIo
reader.readAsArrayBuffer(file.slice(start,end));124Please respect copyright.ＰＥＮＡＮＡX46DP55pKk
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124Please respect copyright.ＰＥＮＡＮＡAOadhSrwEn
Section X. Thanks124Please respect copyright.ＰＥＮＡＮＡB5iGSU3N3F
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]124Please respect copyright.ＰＥＮＡＮＡwK04jyv2W0
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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