javascript - 如果存在则推送到 javascript 数组，如果不存在则先创建它

Question

有没有办法让这一行始终有效而不抛出 TypeError: Cannot read property 'Whatever' of undefined

var MyArray = [];
MyArray[StringVariableName][StringVariableName2].push("whatever");

Answer 1

试试这个:

var MyArray = [];
MyArray[StringVariableName] = MyArray[StringVariableName] || [];
MyArray[StringVariableName][StringVariableName2] = MyArray[StringVariableName][StringVariableName2] || [];
MyArray[StringVariableName][StringVariableName2].push("whatever");