Element.prototype.hasClass = Element.prototype.hasClass || 

  function(classArr){

    var hasClass = 0,

        className = this.getAttribute('class');

  console.log(className);

    if( this == null || !classArr || !className ) return false;

    if( !(classArr instanceof Array) )

      classArr = classArr.split(' ');

​

    for( var i in classArr )

      if( className.split(classArr[i]).length > 1 )  // this.classList.contains(classArr[i])

          hasClass++;

​

    return hasClass == classArr.length;

};

​

​

​

///////////////////////////////

// Tests (see browser's console)

​

var elm1 = document.querySelector('p');

var elm2 = document.querySelector('b');

var elm3 = elm1.firstChild; // textNode

var elm4 = document.querySelector('text'); // SVG text

​

console.log( elm1, ' has class "a": ', elm1.hasClass('a') );

console.log( elm1, ' has class "b": ', elm1.hasClass('b') );

console.log( elm1, ' has class "c": ', elm1.hasClass('c') );

console.log( elm1, ' has class "d": ', elm1.hasClass('d') );

console.log( elm1, ' has class "a c": ', elm1.hasClass('a c') );

console.log( elm1, ' has class "a d": ', elm1.hasClass('a d') );

console.log( elm1, ' has class "": ', elm1.hasClass('') );

​

console.log( elm2, ' has class "a": ', elm2.hasClass('a') );

​

// console.log( elm3, ' has class "a": ', elm3.hasClass('a') );

​

console.log( elm4, ' has class "a": ', elm4.hasClass('a') );