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:158Please respect copyright.ＰＥＮＡＮＡl6Jr1gw4aH
---read whole file content into array buffer---158Please respect copyright.ＰＥＮＡＮＡZq0vF8AWRB
let file=input.files[0]; const reader = new FileReader(); 158Please respect copyright.ＰＥＮＡＮＡ4nnkyOPV5k
reader.onload = () => 158Please respect copyright.ＰＥＮＡＮＡnDD9RVhgId
{158Please respect copyright.ＰＥＮＡＮＡdhIad5TAP5
let content_whole = new Uint8Array(reader.result);158Please respect copyright.ＰＥＮＡＮＡgCt7KALz83
}158Please respect copyright.ＰＥＮＡＮＡ7HwzB7X1Zu
reader.readAsArrayBuffer(file);158Please respect copyright.ＰＥＮＡＮＡtRXKjVagPC
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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:158Please respect copyright.ＰＥＮＡＮＡkkOk3oeERz
---read part of file content into array buffer---158Please respect copyright.ＰＥＮＡＮＡGQpGY4Zymw
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 158Please respect copyright.ＰＥＮＡＮＡ6h00RI8hZW
reader.onload = () => 158Please respect copyright.ＰＥＮＡＮＡ9yuoOcr16i
{158Please respect copyright.ＰＥＮＡＮＡcG3TShrVO0
let content_part = new Uint8Array(reader.result);158Please respect copyright.ＰＥＮＡＮＡbUqsMBfT1j
}158Please respect copyright.ＰＥＮＡＮＡMPKkGo9m4z
reader.readAsArrayBuffer(file.slice(start,end));158Please respect copyright.ＰＥＮＡＮＡR4qcxa4k4m
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158Please respect copyright.ＰＥＮＡＮＡYcVNUU3Yui
Section X. Thanks158Please respect copyright.ＰＥＮＡＮＡzMdql1xIjg
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]158Please respect copyright.ＰＥＮＡＮＡxo9TjWkhmH
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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