Calculate Band NDVI in Google Earth Engine

1. Please navigate to the following URL: https://code.earthengine.google.com/ to webpage in Google Chrome.

2. Please select copy and paste the code below into webpage Code Editor.

// Load an image and display it.
var LC8_image = ee.Image('LANDSAT/LC8_L1T_TOA/LC81250592013178LGN01');
Map.addLayer(LC8_image, {min:0.05, max: 0.8, bands: 'B6, B5, B4'}, "Landsat 8 Scene");
Map.centerObject(LC8_image, 11);

// Create an NDVI image using bands the nir and red bands (5 and 4)
var NDVI = LC8_image.normalizedDifference(['B5','B4']);
// Display the NDVI image Use a grayscale stretch for display
Map.addLayer(NDVI,{min: 0.2, max:0.5, palette: ['FFFFFF', '339900']},"NDVI");