intArrayBounds.js

var testArray1 = [1, 0, -1]; // expected [-1, 1]
var testArray2 = [1, 1, 1, 1, 1, 1]; // expected [1, 1]
var testArray3 = []; //expected []

function getBounds ( intArray ) {
  
    var MIN_INT;
    var MAX_INT;

    if ( intArray.length <= 0 ) return [];

    for ( var i = 0; i < intArray.length; i++ ) {
      
      var currValue = intArray[i];
      MIN_INT = MIN_INT ? ( MIN_INT > currValue ? currValue : MIN_INT ) : currValue;
      MAX_INT = MAX_INT ? ( MAX_INT < currValue ? currValue : MAX_INT ) : currValue;
      
    }
  
    return [ MIN_INT, MAX_INT ];

}

var test1 = getBounds( testArray1 );
var test2 = getBounds( testArray2 );
var test3 = getBounds( testArray3 );

console.log( "Test 1", test1 );
console.log( "Test 2", test2 );
console.log( "Test 3", test3 );