Principle: As long as an object, he had a prototype prototype object, save the properties and methods have in common.
join ( ','). split ( ',') according to the first, converted to a string, and then by, into an array. arrTemp.push (result_str1) return arrTemp; } of arr1 = [. 1, [l, 3], 2 ]; the console.log (arr1.flatten ()) </ Script> </ body> </ HTML>