javascript isArray判断是否数组

Posted 2021-05-04

if (!Array.isArray) {
  Array.isArray = function(arg) {
    return Object.prototype.toString.call(arg) === '[object Array]';
  };
}

isArray为es5特性，兼容ie9及ie9以上

当检测Array实例时, Array.isArray 优于 instanceof,因为Array.isArray能检测iframes.

var iframe = document.createElement('iframe');
document.body.appendChild(iframe);
xArray = window.frames[window.frames.length-1].Array;
var arr = new xArray(1,2,3); // [1,2,3]

// Correctly checking for Array
Array.isArray(arr);  // true
// Considered harmful, because doesn't work though iframes
arr instanceof Array; // false