NodeJS String.replace() problem while filtering - node.js

Question

I can't modify the filtering parameter with
String.replace()
I can get the filtering keys from the URL as an object but its badly fromatted from me.
Filtering: {{URL}}/api/v1/bootcamps?averageCost[lt]=10000
Current format: { averageCost: { lt: '10000' } }
Right fromat: { averageCost: { $lt: '10000' } }
So I tried to convert it as a String and replace that value. But that value can be: lt, lte, gt, gte, in but it has some problem because the line after the .replace() method doesnt executed and of course the catch block cathes the error...
My code snippet:
try {
console.log(req.query);
const queryStr = JSON.stringify(req.query);
console.log(queryStr); //thats the last thing I get
queryStr = queryStr.replace(
/\b(gt|gte|lt|lte|in)\b/g,
match => `$${match}`
);
console.log(queryStr); // I dont get this
const bootcamps = await Bootcamp.find();
res.status(200).json({
succes: true,
count: bootcamps.length,
data: bootcamps
});
} catch (err) {
return res.status(404).json({ succes: false });
}

Answer 1

To replace it correctly you should use something like this:
let queryStr = '{ "averageCost": { "lt": "10000" }, "test": { "gt": "12345"} }';
const regex = /\b(gt|gte|lt|lte|in)\b/g;
queryStr = queryStr.replace(regex, '$$' + "$1"); // <-- here is the correct replace
This will replace queryStr with:
{ "averageCost": { "$lt": "10000" }, "test": { "$gt": "12345"} }
JSFiddle https://jsfiddle.net/c52z8ewr/
If you need the object back just do JSON.parse(queryStr)

Answer 2

You can also Try This
const queryCpy = { ...this.query };
// console.log(queryCpy, 'before filter');
console.log(queryCpy, 'after filter');
let queryString = JSON.stringify(queryCpy);
queryString = queryString.replace(
/\b(gt|gte|lt|lte)\b/g,
(rep) => `$${rep}`,
);
console.log(queryString, 'after filter');

Answer 3

If want an object in return do:
const bootcamps = await Bootcamp.find(JSON.parse(queryStr));