A simple implementation of the DataView ArrayBuffer wrapper.

DataView-polyfill.js

var DataView = (function(){
	var littleEndian = (
		(new Uint16Array((new Uint8Array([0x12, 0x34])).buffer)[0] === 0x3412)
		?true:false); //Determine native endianness

	function dv(buffer){
		this.buffer = buffer;
		this.bytes = new Uint8Array(buffer);
	}

	dv.prototype = {
		getU8 : function(offset) {
			return this.bytes[offset];
		},
		getI8 : function(offset) {
			return this.bytes[offset] - 1<<7;
		},
		getU16 : function(offset, le) {
			if(le==littleEndian){ //if desired endianness matches native endianness
				return (new Uint16Array(this.buffer,offset,2))[0];
			}
			return (le //otherwise, do the expansion 'by hand'
				?(this.bytes[offset+1] << 8) | this.bytes[offset]
				:(this.bytes[offset] << 8) | this.bytes[offset+1]
			);
		},
		getI16 : function(offset, le) {
			if(le==littleEndian){
				return (new Int16Array(this.buffer,offset,2))[0];
			}
			return  (le
				?(this.bytes[offset+1] << 8) | this.bytes[offset]
				:(this.bytes[offset] << 8) | this.bytes[offset+1]
			) - 1<<15;
		},
		getU32 : function(offset, le) {
			if(le==littleEndian){
				return (new Uint32Array(this.buffer,offset,4))[0];
			}
			return (le
				?(this.bytes[offset+3] << 24) | (this.bytes[offset+2] << 16) | (this.bytes[offset+1] << 8) | this.bytes[offset]
				:(this.bytes[offset] << 24) | (this.bytes[offset+1] << 16) | (this.bytes[offset+2] << 8) | this.bytes[offset+3]
			);
		},
		getI32 : function(offset, le) {
			if(le==littleEndian){
				return (new Int32Array(this.buffer,offset,4))[0];
			}
			return (le
				?(this.bytes[offset+3] << 24) | (this.bytes[offset+2] << 16) | (this.bytes[offset+1] << 8) | this.bytes[offset]
				:(this.bytes[offset] << 24) | (this.bytes[offset+1] << 16) | (this.bytes[offset+2] << 8) | this.bytes[offset+3]
			) - 1<<31;
		}
	};
	
	return dv;
}());