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:160Please respect copyright.ＰＥＮＡＮＡgi8ugjxvcu
---read whole file content into array buffer---160Please respect copyright.ＰＥＮＡＮＡZsqL0NVC1q
let file=input.files[0]; const reader = new FileReader(); 160Please respect copyright.ＰＥＮＡＮＡIXqavx3g3E
reader.onload = () => 160Please respect copyright.ＰＥＮＡＮＡtSoXw4v37l
{160Please respect copyright.ＰＥＮＡＮＡYuM54fPRYs
let content_whole = new Uint8Array(reader.result);160Please respect copyright.ＰＥＮＡＮＡ3Do3byIP8S
}160Please respect copyright.ＰＥＮＡＮＡXRwPa6q4Z8
reader.readAsArrayBuffer(file);160Please respect copyright.ＰＥＮＡＮＡABBTp788Mr
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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:160Please respect copyright.ＰＥＮＡＮＡ07EZ8O7mTG
---read part of file content into array buffer---160Please respect copyright.ＰＥＮＡＮＡ7apokSnCHZ
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 160Please respect copyright.ＰＥＮＡＮＡS4x8991zQf
reader.onload = () => 160Please respect copyright.ＰＥＮＡＮＡq71rgkYSy1
{160Please respect copyright.ＰＥＮＡＮＡmHATNN1ZbM
let content_part = new Uint8Array(reader.result);160Please respect copyright.ＰＥＮＡＮＡkVTBx2lk1x
}160Please respect copyright.ＰＥＮＡＮＡ31EMnclrCq
reader.readAsArrayBuffer(file.slice(start,end));160Please respect copyright.ＰＥＮＡＮＡ3WhcPHORid
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160Please respect copyright.ＰＥＮＡＮＡZbHOa61wNz
Section X. Thanks160Please respect copyright.ＰＥＮＡＮＡq6KwiNfRAz
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]160Please respect copyright.ＰＥＮＡＮＡDc1xlY2Mry
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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