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:146Please respect copyright.ＰＥＮＡＮＡjaKd7FwDvM
---read whole file content into array buffer---146Please respect copyright.ＰＥＮＡＮＡWaNr7c6UQ4
let file=input.files[0]; const reader = new FileReader(); 146Please respect copyright.ＰＥＮＡＮＡSqxgtS8b81
reader.onload = () => 146Please respect copyright.ＰＥＮＡＮＡTlCwhPO5GR
{146Please respect copyright.ＰＥＮＡＮＡMq7Ymz2rv7
let content_whole = new Uint8Array(reader.result);146Please respect copyright.ＰＥＮＡＮＡ6WnnL8LIZp
}146Please respect copyright.ＰＥＮＡＮＡ9Pr7jMrZa5
reader.readAsArrayBuffer(file);146Please respect copyright.ＰＥＮＡＮＡ3TuVca5kaq
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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:146Please respect copyright.ＰＥＮＡＮＡEfzRoyjKsY
---read part of file content into array buffer---146Please respect copyright.ＰＥＮＡＮＡmmYwtIm5rZ
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 146Please respect copyright.ＰＥＮＡＮＡy2CZRziZzX
reader.onload = () => 146Please respect copyright.ＰＥＮＡＮＡCppbXBluOz
{146Please respect copyright.ＰＥＮＡＮＡRWxdfm6PKp
let content_part = new Uint8Array(reader.result);146Please respect copyright.ＰＥＮＡＮＡkAjp07RTUt
}146Please respect copyright.ＰＥＮＡＮＡR7oGrNd3j0
reader.readAsArrayBuffer(file.slice(start,end));146Please respect copyright.ＰＥＮＡＮＡ61QCMR6KyR
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146Please respect copyright.ＰＥＮＡＮＡ8NQcoRfQhY
Section X. Thanks146Please respect copyright.ＰＥＮＡＮＡoMv4eW6IaL
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]146Please respect copyright.ＰＥＮＡＮＡoC3PkFGpUh
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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