how to give error in catch block in javascript code example

Example 1: try catch in javascript

try {
  // Try to run this code 
}
catch(err) {
  // if any error, Code throws the error
}
finally {
  // Always run this code regardless of error or not
  //this block is optional
}

Example 2: javascript try

var someNumber = 1;
try {
  someNumber.replace("-",""); //You can't replace a int
} catch(err) {
 console.log(err);
}