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:50Please respect copyright.ＰＥＮＡＮＡhIc9CIk5ZQ
---read whole file content into array buffer---50Please respect copyright.ＰＥＮＡＮＡvOr1xbssJC
let file=input.files[0]; const reader = new FileReader(); 50Please respect copyright.ＰＥＮＡＮＡ9wQHrLV0B3
reader.onload = () => 50Please respect copyright.ＰＥＮＡＮＡO7YaaM7zEl
{50Please respect copyright.ＰＥＮＡＮＡ8ds6LpJnPF
let content_whole = new Uint8Array(reader.result);50Please respect copyright.ＰＥＮＡＮＡBRxr52PuiS
}50Please respect copyright.ＰＥＮＡＮＡEGoEOQgslk
reader.readAsArrayBuffer(file);50Please respect copyright.ＰＥＮＡＮＡhB45iRIykJ
-----------------------------------------------
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:50Please respect copyright.ＰＥＮＡＮＡiLt3y3lxDt
---read part of file content into array buffer---50Please respect copyright.ＰＥＮＡＮＡ25mfd8w64k
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 50Please respect copyright.ＰＥＮＡＮＡeOEfFeTpBN
reader.onload = () => 50Please respect copyright.ＰＥＮＡＮＡtlOgWV3jXz
{50Please respect copyright.ＰＥＮＡＮＡIYUZKA68xu
let content_part = new Uint8Array(reader.result);50Please respect copyright.ＰＥＮＡＮＡjufF1tf6Rt
}50Please respect copyright.ＰＥＮＡＮＡZwY0Ev06y8
reader.readAsArrayBuffer(file.slice(start,end));50Please respect copyright.ＰＥＮＡＮＡQqRr1BSa51
-----------------------------------------------
50Please respect copyright.ＰＥＮＡＮＡmmweazlRVd
Section X. Thanks50Please respect copyright.ＰＥＮＡＮＡMKoQ6yzqsm
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]50Please respect copyright.ＰＥＮＡＮＡ8Spk5t8Djo
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]
如果您對C/C++ Programming, Linux, HTTP Protocol, Website Development, Vue, Git, VsCode感興趣，邀請您加入「Linux/C/C++ Website Development」微信群，請加我的微信（si_jinmin）以便拉您进群。
ns18.118.171.161da2
