I have written a code for Palindrome problem
i am getting an error for a line that does not exist
can anyone assist me on this?

CODE:
'''
class Solution
{
constructor(x)
{
this.x=x;
}

	convert_num_to_array(num)
	{
		var arr = [];
    
		while (num>0)
		{
			arr.push(num%10); // push ones
			num/=10; // remove ones
			let remainder=num%1; //set remainder 
			num-=remainder;//round number [remove remainder]
		}
    
		return arr; //return array of converted number
	}


	isPalindrome()
	{
		var arr = [];
		arr = this.convert_num_to_array(this.x);
		 // printArr(arr);
		let i=0, j=arr.length-1;
		while(i!=j){
			if(arr[i]!=arr[j])
				{
					return false;
				}
			else
				{
					i++;
					j--;
				}
		}
		return true;
	}

}

param_1 = 121;
var x=new Solution(param_1);

var ret = x.isPalindrome();
console.log(ret);

'''

(code only reaches line 52)
ERROR MSG:
Line 62 in solution.js
var ret = isPalindrome(param_1);
^
ReferenceError: isPalindrome is not defined
Line 62: Char 19 in solution.js (Object.)
Line 16: Char 8 in runner.js (Object.runner)
Line 53: Char 26 in solution.js (Object.)
at Module._compile (node:internal/modules/cjs/loader:1101:14)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
at Module.load (node:internal/modules/cjs/loader:981:32)
at Function.Module._load (node:internal/modules/cjs/loader:822:12)
at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
at node:internal/main/run_main_module:17:47