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:172Please respect copyright.PENANAYHnAre8xjC
---read whole file content into array buffer---172Please respect copyright.PENANAz5b3D3xa2V
let file=input.files[0]; const reader = new FileReader(); 172Please respect copyright.PENANAmoar5tEBcB
reader.onload = () => 172Please respect copyright.PENANAgMmf2fZjLy
{172Please respect copyright.PENANAI2cucSeLjC
let content_whole = new Uint8Array(reader.result);172Please respect copyright.PENANAdynDFtCLpH
}172Please respect copyright.PENANAU03zJmglMC
reader.readAsArrayBuffer(file);172Please respect copyright.PENANAdczpe9FBe7
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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:172Please respect copyright.PENANAHqwfBq8kz1
---read part of file content into array buffer---172Please respect copyright.PENANAdRAgJxNM2H
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 172Please respect copyright.PENANAZJCFuihaG0
reader.onload = () => 172Please respect copyright.PENANAOiYY30pYJb
{172Please respect copyright.PENANA3xrKZOEF84
let content_part = new Uint8Array(reader.result);172Please respect copyright.PENANA6PXB5YCEd1
}172Please respect copyright.PENANASsCp047QVP
reader.readAsArrayBuffer(file.slice(start,end));172Please respect copyright.PENANAXqmf9BKEfI
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172Please respect copyright.PENANAjEqylEUygV
Section X. Thanks172Please respect copyright.PENANAxrToDdp3Ch
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]172Please respect copyright.PENANAwv6UgPHOxT
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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