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:151Please respect copyright.ＰＥＮＡＮＡNexcEDRNny
---read whole file content into array buffer---151Please respect copyright.ＰＥＮＡＮＡOYKaoYld18
let file=input.files[0]; const reader = new FileReader(); 151Please respect copyright.ＰＥＮＡＮＡZsuxSHTHUD
reader.onload = () => 151Please respect copyright.ＰＥＮＡＮＡI5vsNDBxnX
{151Please respect copyright.ＰＥＮＡＮＡTAEtAAxXIc
let content_whole = new Uint8Array(reader.result);151Please respect copyright.ＰＥＮＡＮＡaADCpTHjHM
}151Please respect copyright.ＰＥＮＡＮＡ3Gvf0fkmiY
reader.readAsArrayBuffer(file);151Please respect copyright.ＰＥＮＡＮＡ1Tn6AfflKN
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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:151Please respect copyright.ＰＥＮＡＮＡDVAYcMMHq0
---read part of file content into array buffer---151Please respect copyright.ＰＥＮＡＮＡ9kIR8Mtim2
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 151Please respect copyright.ＰＥＮＡＮＡ9nGANcpFJs
reader.onload = () => 151Please respect copyright.ＰＥＮＡＮＡUqXxsLr0w9
{151Please respect copyright.ＰＥＮＡＮＡURT2uLewzc
let content_part = new Uint8Array(reader.result);151Please respect copyright.ＰＥＮＡＮＡu6oSczVqGO
}151Please respect copyright.ＰＥＮＡＮＡkU41VIolOF
reader.readAsArrayBuffer(file.slice(start,end));151Please respect copyright.ＰＥＮＡＮＡM69yGJwIBS
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151Please respect copyright.ＰＥＮＡＮＡO6FudxKTo4
Section X. Thanks151Please respect copyright.ＰＥＮＡＮＡtFfwygPq9E
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]151Please respect copyright.ＰＥＮＡＮＡp0RPpPRUy1
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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