If( a==1 && a==2&&a==3 ) is equal to true under what circumstances?

//Using the principle of data hijacking, ES6 proxy can also be implemented let bValue = 1; Object.defineProperty(window, "a", { get() { return bValue++; } }); if(a == 1 && a == 2 && a == 3) { console.log("Hello World!"); } 

let test = { number: 1 }; test = new Proxy(test, { get(target, key) { return target[key]++; } }); if(test.number === 1 && test.number ===2 && test.number ===3){ console.log('Hello World!'); } 

let a = [1, 2, 3]; //Use the array method shift to override toString, take the first element of the array and return a.toString = a.shift; if (a == 1 && a == 2 && a == 3) { console.log("Hello World!"); } //Override toString method let a = { bValue: 1, toString: ()=> { return a.bValue++; } } if (a == 1 && a == 2 && a == 3) { console.log("Hello World!"); } 

let a = [1, 2, 3]; //Use the array method shift to override valueOf, take the first element of the array and return a.valueOf = a.shift; if (a == 1 && a == 2 && a == 3) { console.log("Hello World!"); } / ** * Override valueOf method */ let a = { bValue: 1, valueOf: ()=> { return a.bValue++ } }; if (a == 1 && a == 2 && a == 3) { console.log("Hello World!"); }