Arrays not updating in Service

Is there any reason why an array would not be updated in the service ?

Also, on second execution of this code, the comment count remains the same.

And on pushing the new comment returns “range error : max call stack exceeded”.

` let comments = […this.comments];
let new_comment_id:number = 0;

			new_comment_id = comments[0].comment_ID+1;

	    	let comment = {comment_ID:new_comment_id,...new_comment};

	    	console.log('inside service '+this.comments.length);`
	    	this.comments = comments;
	    	console.log('inside service after unshift '+this.comments.length);` 

I am stuck on this bug for days now.