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:129Please respect copyright.ＰＥＮＡＮＡ3EMXuIGRYb
---read whole file content into array buffer---129Please respect copyright.ＰＥＮＡＮＡ0O25jSN550
let file=input.files[0]; const reader = new FileReader(); 129Please respect copyright.ＰＥＮＡＮＡDY3v4OWY3e
reader.onload = () => 129Please respect copyright.ＰＥＮＡＮＡ6qpTTbBa1y
{129Please respect copyright.ＰＥＮＡＮＡadxVnNfM5M
let content_whole = new Uint8Array(reader.result);129Please respect copyright.ＰＥＮＡＮＡADg3J5leP5
}129Please respect copyright.ＰＥＮＡＮＡ7ScYrtabNg
reader.readAsArrayBuffer(file);129Please respect copyright.ＰＥＮＡＮＡumjG6VeNN9
-----------------------------------------------
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:129Please respect copyright.ＰＥＮＡＮＡxnNeEUJfTb
---read part of file content into array buffer---129Please respect copyright.ＰＥＮＡＮＡurhFzVRDO5
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 129Please respect copyright.ＰＥＮＡＮＡSlJHgckboF
reader.onload = () => 129Please respect copyright.ＰＥＮＡＮＡihJu4NThNG
{129Please respect copyright.ＰＥＮＡＮＡ4sdO8eovtk
let content_part = new Uint8Array(reader.result);129Please respect copyright.ＰＥＮＡＮＡwmtg6Zx8ZC
}129Please respect copyright.ＰＥＮＡＮＡGOsIHbMfD5
reader.readAsArrayBuffer(file.slice(start,end));129Please respect copyright.ＰＥＮＡＮＡaUQ9ZpLX9t
-----------------------------------------------
129Please respect copyright.ＰＥＮＡＮＡemenTPLAub
Section X. Thanks129Please respect copyright.ＰＥＮＡＮＡHlWA1P58hw
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]129Please respect copyright.ＰＥＮＡＮＡpr1cDvm4St
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。
ns216.73.216.51da2
