Решения для тестового задания под пунктом 4

gistfile1.js

var obj = {
    index: 0,
    words: ['blackberry', 'apple', 'orange'],
    callCount: 0,
    toString: function() {
        this.callCount++;
        this.index = this.index > this.words.length - 2 ? 0 : this.index + 1;
        return ( this.callCount === 2 ? ' ' : '') + this.words[this.index] ;
    }
};

console.log('2 ' + obj === '2 apple');

console.log('as is' + obj === 'as is orange');

console.log(obj + ' is bad' === 'blackberry is bad');

console.log(obj + ' is cool' === 'apple is cool');

console.log(obj + ' color' === 'orange color');