function isBinaryString( str ) {
	var ch;
	var i;
	if ( !isString( str ) ) {
		return false;
	}
	if ( str.length === 0 ) {
		return false;
	}
	for ( i = 0; i < str.length; i++ ) {
		ch = str[ i ];
		if ( ch !== '1' && ch !== '0' ) {
			return false;
		}
	}
	return true;
}
Tests if a value is a binary string.

@param {*} str - value to test
@returns {boolean} boolean indicating if an input value is a binary string

@example
var bool = isBinaryString( '1000101' );
// returns true

@example
var bool = isBinaryString( 'beep' );
// returns false

@example
var bool = isBinaryString( '' );
// returns false