When to use obj['attribute name'] for the attribute name of an object

The composition of the object ：
attribute ： Property name （ character string ）, And property values （ arbitrarily ） form
Method ： Is a special attribute , Only the attribute value is a function .
Object access ：

1. **·** Property name ： The coding is simple , Sometimes it doesn't work
2. [‘ Property name ’]： Coding trouble , Can be universal . From the bottom .