Remove specific characters from a long string Typescript

Looks like part of the problem is your CamlQuer needs additional escapes and to match the casing of camlQuer below.

Next, the split method does not modify the variable directly, so you need to reassign the output.

These change would make your code look like:

var camlQuer = "{\"$o_1\":true,\"$N_1\":\"<View><ViewFields><FieldRef Name=\"Title\" /><FieldRef Name=\"Date1\" /></ViewFields><Joins><Join Type=\"LEFT\" ListAlias=\"Workshop\"><Eq><FieldRef Name=\"WorkshopResult\" RefType=\"ID\" /><FieldRef Name=\"ID\" List=\"Workshop\" /></Eq></Join></Joins><ProjectedFields><Field ShowField=\"Workshop\" Type=\"Lookup\" Name=\"Title\" List=\"Workshop\" /></ProjectedFields><Query><Where /></Query></View>\"}"

camlQuer = camlQuer.split('"$o_1":true,"$N_1":"').join('');
console.log(camlQuer)

However, you would be better off using the replace method which is meant to remove or replace a string of characters. Your code would then look like:

var camlQuer = "{\"$o_1\":true,\"$N_1\":\"<View><ViewFields><FieldRef Name=\"Title\" /><FieldRef Name=\"Date1\" /></ViewFields><Joins><Join Type=\"LEFT\" ListAlias=\"Workshop\"><Eq><FieldRef Name=\"WorkshopResult\" RefType=\"ID\" /><FieldRef Name=\"ID\" List=\"Workshop\" /></Eq></Join></Joins><ProjectedFields><Field ShowField=\"Workshop\" Type=\"Lookup\" Name=\"Title\" List=\"Workshop\" /></ProjectedFields><Query><Where /></Query></View>\"}"

camlQuer = camlQuer.replace('"$o_1":true,"$N_1":"', '');
console.log(camlQuer)

My approach in order to "escape" the string

let regexp = new RegExp(camlQuer);

Using Nick solution

let regexp = new RegExp(camlQuer);
console.log(camlQuer);
camlQuer = camlQuer.replace('"$o_1":true,"$N_1":"', '');