three.js/src/extras/ImageUtils.js

var ImageUtils = {

	loadTexture: function ( path, mapping, callback ) {

		var image = new Image(),
			texture = new THREE.Texture( image, mapping );

		image.onload = function () { texture.needsUpdate = true; if( callback ) callback( this ); };
		image.src = path;

		return texture;

	},

	loadTextureCube: function ( array, mapping, callback ) {

		var i, l, 
			images = [],
			texture = new THREE.Texture( images, mapping );

		images.loadCount = 0;

		for ( i = 0, l = array.length; i < l; ++i ) {

			images[ i ] = new Image();
			images[ i ].onload = function () {

					images.loadCount += 1; 
					if( images.loadCount == 6 ) texture.needsUpdate = true; 
					if( callback ) callback( this ); 

				};

			images[ i ].src = array[ i ];

		}

		return texture;

	}

};