jsオブジェクト属性名の書き方

Notation of Keys

var test = {     'case': 'I am a keyword so I must be notated as a string',     delete: 'I am a keyword too so me' // raises SyntaxError }; 

Object properties can be both notated a s plane characters and as strigs.Due to another mis-design JavaScript's parser,the above will throw a SyntaxError pror to ECMAScript 5.
This error arrises from the fact that 
delete is a keyword;therefore,it must be notated as a string lieral to ensure that it will be corectly interpreted by older JavaScript engies.