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I have an image file in the form of a JavaScript File object. I was to add it to an <img> tag so I can render it in my React project. This is going to be used in my Client side code so I do not want it to be downloaded. I was looking at a few similar (but not exact) questions and they all use a FileReader but I cannot seem to get it to work. I keep getting an ImagePreview.js:25 Uncaught TypeError: Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'.. My object is a File object which is a type of Blob according to the Mozilla document. Maybe I am confused? Could someone point me in the right direction? This is what the object looks like when I print it to the console:

File {name: 'gopher1.png', lastModified: 1633647754682, lastModifiedDate: Thu Oct 07 2021 18:02:34 GMT-0500 (Central Daylight Time), webkitRelativePath: '', size: 34156, …}
lastModified: 1633647754682
lastModifiedDate: Thu Oct 07 2021 18:02:34 GMT-0500 (Central Daylight Time) {}
name: "gopher1.png"
size: 34156
type: ""
webkitRelativePath: ""
[[Prototype]]: File

I have an image file in the form of a JavaScript File object. I was to add it to an <img> tag so I can render it in my React project. This is going to be used in my Client side code so I do not want it to be downloaded. I was looking at a few similar (but not exact) questions and they all use a FileReader but I cannot seem to get it to work. I keep getting an ImagePreview.js:25 Uncaught TypeError: Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'.. My object is a File object which is a type of Blob according to the Mozilla document. Maybe I am confused? Could someone point me in the right direction? This is what the object looks like when I print it to the console:

File {name: 'gopher1.png', lastModified: 1633647754682, lastModifiedDate: Thu Oct 07 2021 18:02:34 GMT-0500 (Central Daylight Time), webkitRelativePath: '', size: 34156, …}
lastModified: 1633647754682
lastModifiedDate: Thu Oct 07 2021 18:02:34 GMT-0500 (Central Daylight Time) {}
name: "gopher1.png"
size: 34156
type: ""
webkitRelativePath: ""
[[Prototype]]: File

• javascript
• reactjs

Share Improve this question Follow asked Oct 7, 2021 at 23:19 Notorious776Notorious776 50399 silver badges2525 bronze badges 3

• 1 Can you share a code sandbox with a demo of what you have so far in terms of code? – gacanepa Commented Oct 8, 2021 at 0:34
• 2 You are certainly not passing what you think to this method, but note that you should not use a FileReader here anyway. To render the image from the Blob, create a blob URL. – Kaiido Commented Oct 8, 2021 at 2:10
• @Kaiido this is exactly what I am looking for! Had to do a few tweaks but it works, thank you! – Notorious776 Commented Oct 8, 2021 at 5:42

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1 Answer 1

Sorted by: Reset to default 6

I believe you do

const url = URL.createObjectURL(file)

then use url as a src

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