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:66Please respect copyright.ＰＥＮＡＮＡWzTzxwzw5L
---read whole file content into array buffer---66Please respect copyright.ＰＥＮＡＮＡboeaArfXdW
let file=input.files[0]; const reader = new FileReader(); 66Please respect copyright.ＰＥＮＡＮＡH8MZjG5V2g
reader.onload = () => 66Please respect copyright.ＰＥＮＡＮＡylTNxoAZXy
{66Please respect copyright.ＰＥＮＡＮＡtrW1z9MqY0
let content_whole = new Uint8Array(reader.result);66Please respect copyright.ＰＥＮＡＮＡfo0hv1fz4b
}66Please respect copyright.ＰＥＮＡＮＡT8Fhiow5vI
reader.readAsArrayBuffer(file);66Please respect copyright.ＰＥＮＡＮＡU2FHViH67A
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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:66Please respect copyright.ＰＥＮＡＮＡIYFUQqAoS5
---read part of file content into array buffer---66Please respect copyright.ＰＥＮＡＮＡlbWVI0V2o3
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 66Please respect copyright.ＰＥＮＡＮＡDO3A0DYsOO
reader.onload = () => 66Please respect copyright.ＰＥＮＡＮＡ6Cv0ANrugI
{66Please respect copyright.ＰＥＮＡＮＡWP9hXSpKP6
let content_part = new Uint8Array(reader.result);66Please respect copyright.ＰＥＮＡＮＡmP6ZPOCzjj
}66Please respect copyright.ＰＥＮＡＮＡG4mqfjBjDX
reader.readAsArrayBuffer(file.slice(start,end));66Please respect copyright.ＰＥＮＡＮＡsBAmb8lBi4
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66Please respect copyright.ＰＥＮＡＮＡcwqyLN4FlL
Section X. Thanks66Please respect copyright.ＰＥＮＡＮＡCKRAYSYRwP
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]66Please respect copyright.ＰＥＮＡＮＡ26MlFf3spV
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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