maximum element in an array code example

Example 1: array with objects read element with the lowest value

myArray.reduce(function(prev, curr) {
    return prev.Cost < curr.Cost ? prev : curr;
});

Example 2: kth largest element in an array javascript

function nthlargest(arra,highest){
			var x = 0,
				y = 0,
				z = 0,
				temp = 0,
				tnum = arra.length, 
				flag = false, 
				result = false; 
   
			while(x < tnum){
				y = x + 1; 
				
				if(y < tnum){
					for(z = y; z < tnum; z++){
						
						if(arra[x] < arra[z]){
							temp = arra[z];
							arra[z] = arra[x];
							arra[x] = temp;
							flag = true; 
						}else{
							continue;
						}	
					}					
				}
				
				if(flag){
					flag = false;
				}else{
					x++; 
					if(x === highest){ 
                      
						result = true;
					}	
				}
				if(result){
					break;
				}
			}

			return (arra[(highest - 1)]);	
		}
		
console.log(nthlargest([ 43, 56, 23, 89, 88, 90, 99, 652], 4));