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:143Please respect copyright.ＰＥＮＡＮＡz7yzb9sKAt
---read whole file content into array buffer---143Please respect copyright.ＰＥＮＡＮＡ84lTi1v98C
let file=input.files[0]; const reader = new FileReader(); 143Please respect copyright.ＰＥＮＡＮＡtXHNyCyKa4
reader.onload = () => 143Please respect copyright.ＰＥＮＡＮＡhJWNf1ScH1
{143Please respect copyright.ＰＥＮＡＮＡ9CAGBO5Spq
let content_whole = new Uint8Array(reader.result);143Please respect copyright.ＰＥＮＡＮＡiGOz48ttnw
}143Please respect copyright.ＰＥＮＡＮＡ6i81iLWOvE
reader.readAsArrayBuffer(file);143Please respect copyright.ＰＥＮＡＮＡvuOStoiAQO
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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:143Please respect copyright.ＰＥＮＡＮＡH5XdxGdmb6
---read part of file content into array buffer---143Please respect copyright.ＰＥＮＡＮＡW7MCwscUSF
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 143Please respect copyright.ＰＥＮＡＮＡVKUfV18dwN
reader.onload = () => 143Please respect copyright.ＰＥＮＡＮＡK165ohpMsy
{143Please respect copyright.ＰＥＮＡＮＡoHKED5MExR
let content_part = new Uint8Array(reader.result);143Please respect copyright.ＰＥＮＡＮＡu2npKJMN3i
}143Please respect copyright.ＰＥＮＡＮＡqZxW3EzGBi
reader.readAsArrayBuffer(file.slice(start,end));143Please respect copyright.ＰＥＮＡＮＡQmSkR6ZBeJ
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143Please respect copyright.ＰＥＮＡＮＡEkgPl2qd51
Section X. Thanks143Please respect copyright.ＰＥＮＡＮＡAZtGoxLhOf
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]143Please respect copyright.ＰＥＮＡＮＡtZtwEm9Pya
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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