JavaScript log parser project: Bad idea?

Question

There are numerous log files that I have to review daily for my job. Several good parsers already exist for these log files but I have yet to find exactly what I want. Well, who could make something more tailored to you than you, right?

The reason I am using JavaScript (other than the fact that I already know it) is because it's portable (no need to install anything) but at the same time cross-platform accessible. Before I invest too much time in this, is this a terrible method of accomplishing my goal?

1. The input will be entered into a text file, delimited by [x] and the values will be put into an array to make accessing these values faster than pulling the static content.
2. Any special formatting (numbers, dates, etc) will be dealt with before putting the value in the array to prevent a function from repeating this step every time it is used.
3. These logs may contain 100k+ lines which will be a lot for the browser to handle. However, each line doesn't contain a ton of information.
4. I have written some of it already, but with even 10,000 lines it's starting to run slow and I don't know if it's because I wasn't efficient enough or if this just cannot be effectively done. I'm thinking this is because all the data is in one giant table. I'd probably be better off paginating it, but that is less than desirable.

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Question 1: Is there anything I failed to mention that I should consider?
Question 2: Would you recommend a better alternative?
Question 3: (A bit off topic, so feel free to ignore). Instead of copy/pasting the input, I would like to 'open' the log file but as far as I know JavaScript cannot do this (for security reasons). Can this be accomplished with a input="file" without actually having a server to upload to? I don't know how SSJS works, but it appears that I underestimated the limitations of JavaScript.

I understand this is a bit vague, but I'm trying to keep you all from having to read a book to answer my question. Let me know if I should include additional details. Thanks!