？位置怎么写才能输出true

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

考点：== 运算符的运算规则，类型转换的规则

var obj = {
    };
console.log(obj.valueOf()) //{} 非原始类型
console.log(obj.toString()) //'[object Object]'

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

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

所以正解为

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

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

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