var iframe = document.createElement('iframe');
    
document.body.appendChild(iframe);
var xArray = window.frames[window.frames.length - 1].Array
var arr = new xArray(1, 2, 3)
console.log(arr)
// Correctly checking for Array
console.log(Array.isArray(arr));  // true
console.log(Object.prototype.toString.call(arr)); // true
// Considered harmful, because doesn't work though iframes
console.log(arr instanceof Array); // false
console 命令行工具 X clear
console