How do I replace substrings in my string with array objects?

Question

I am trying to replace special characters in a string, with the string being file names as special characters cannot be stored on the Windows filesystem.

What I have tried is simply using replace() on my variable repeatedly until it covers all of the special characters I want to replace. Example code:

//Formats file name to save to Filesystem
function formatFileName(postTitle, postUrl, nsfw) {
return new Promise(resolve => {
    //Filter out bad characters
    postTitle = postTitle.replace(/\?/g, "[q]");
    postTitle = postTitle.replace(/\//g, "[s]");
    postTitle = postTitle.replace(/\</g, "[l]");
    postTitle = postTitle.replace(/\>/g, "[m]");
    postTitle = postTitle.replace(/\"/g, "[quo]");
    postTitle = postTitle.replace(/\*/g, "[st]");

While this works, I know that there is definitely a better way out there to do this, and as such, I'd like to find out how I could do so in a cleaner manner.

I've tried refining the code by doing this instead:

    let specialCharacters = ["?", "/", "<", ">", "\"", "*", "\\"];
    let replacement = ["[q]", "[s]", "[l]", "[m]", "[quo]", "[st]", "[bs]"];

    //Replace special characters into filesystem-compatible ones
    for (var i = 0; i < specialCharacters.length; i++) {
        postTitle.replace(specialCharacters[i], replacement[i]);
    }

However, with the newly modified code, it does not replace any of the special characters in the string. I've also tried doing

    let specialCharacters = [/\?/g, /\//g, /\</g, /\>/g, /\"/g, /\*/g, /\\/g];
    let replacement = ["[q]", "[s]", "[l]", "[m]", "[quo]", "[st]", "[bs]"];

    //Replace special characters into filesystem-compatible ones
    for (var i = 0; i < specialCharacters.length; i++) {
        postTitle.replace(specialCharacters[i], replacement[i]);
    }
    console.log(postTitle);
    resolve(postTitle);

but the outcome did not change. Another thing I tried was to wrap it in an async/await function as I thought that it may be because NodeJS wasn't waiting for the loop to finish, but that did not change anything either.

Could someone please tell me what I'm doing wrong?

I think the need to sanitize a filename is kinda common. You CAN write your own, but others have already done this. See google.com/search?q=node+js+sanitize+filename — Nikki9696
– Nikki9696, Commented Jan 3, 2020 at 16:02

pascalpuetz · Accepted Answer · 2020-01-03 16:00:38Z

2

Strings in JavaScript are immutable. You are not reassigning the returned value from replace.

let specialCharacters = [/\?/g, /\//g, /\</g, /\>/g, /\"/g, /\*/g, /\\/g];
let replacement = ["[q]", "[s]", "[l]", "[m]", "[quo]", "[st]", "[bs]"];

//Replace special characters into filesystem-compatible ones
for (var i = 0; i < specialCharacters.length; i++) {
  // Assign return value to postTitle
  postTitle = postTitle.replace(specialCharacters[i], replacement[i]);
}
console.log(postTitle);

answered Jan 3, 2020 at 16:00

pascalpuetz

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2 Comments

Garlicvideos Over a year ago

BRUH. I feel so stupid for not realising this lmao. Thanks!

pascalpuetz Over a year ago

You're welcome - actually a pretty common mistake :)

Tân · Accepted Answer · 2020-01-03 16:21:19Z

0

You can try this way:

var specialCharacters = ['?', '/', '<', '>', '"', '*', '\\'];
var replacement = ["[q]", "[s]", "[l]", "[m]", "[quo]", "[st]", "[bs]"];

var pattern = new RegExp(specialCharacters.map(x => '(\\' + x + ')').join('|'), 'g');

var str = "<span>What is your question?</span>";

console.log(str.replace(pattern, x => replacement[specialCharacters.indexOf(x)]));

answered Jan 3, 2020 at 16:21

Tân

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