？ How to write the position to output true

var a = ?;
console.log(
	a == 1 &&
	a == 2 &&
	a == 3
)

Examination site ：== The operation rules of operators , Rules for type conversion

var obj = {
    };
console.log(obj.valueOf()) //{}  Non primitive type 
console.log(obj.toString()) //'[object Object]'

 therefore 
obj == 1 //false
obj == '[object Object]' // true

var obj = {
    
	valueOf: function() {
    
		return 1
	}
};
obj == 1 //true

So the positive solution is

a = {
    
	n: 1,
	valueOf: function(){
    
		return this.n++
	}
}

Change questions : console.log(a == 1 &&a == 2 &&a == 4)

a = {
    
	n: [1,2,4],
	i:0,
	valueOf: function(){
    
		return this.n[this.i++]
	}
}