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Forums Adobe After Effects Expressions Parsing JSON Files – Fastest possible way?

  • Parsing JSON Files – Fastest possible way?

  • Andrei Popa

    September 13, 2021 at 7:53 am

    Hi Tomas. I think I got confused at some point with my answers. I just checked on my code and I use $.evalFile() to read the json’s. I remember doing some tests and that I used what was fastest. This is how I use it:

    var alpha = $.evalFile(File("path/to/file/json.json"));

    However, if you ever need to take the whole content of a file again, I suggest reading it with

    var str =;

    It reads the whole file in one go.

    Here is a link with the description, page 53

    JavaScript Tools Guide (

    I don’t think evalFile will work with the new expressions engine so maybe you will need to use the eval([string]) version if you want to use it in expressions.

  • Tomas Bumbulevičius

    October 27, 2021 at 6:26 am

    Hey Andrei, thanks for your response. I didn’t had time to focus on this recently, but few thoughts:
    1. When contents of file is read as – I assume its a plain binary read. Then, what to do with that readed bits, how to make them human-readable?
    2. Indeed, dollar like $.evalFile is obsolete and doesn’t work if expression language set to new Javascript. While I am looking how to approach this in scripting, if someone hits that roadblock through expressions – be aware that $.evalFile in expressions works only with expression engine set to “Legacy Extendscript”. While its not a new thing, I just figured out it recently.

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