Write a function to test if a sentence is a symmetric sentence. (function will return true or false) Symmetric sentence examples: 

1. Live not on evil (-> livenotonevil symmetric sentence) 

2. Step on no pets (-> steponnopets symmetric sentence) 

3. Too bad I hid a boot (-> toobadihidaboot symmetric sentence) 

4. Evil olive (-> evilolive symmetric sentence) 

5. Borrow or rob (-> borroworrob symmetric sentence) 

6. Hello world (->helloworld NOT symmetric sentence) 

Use  javascript format and include test cases calling the checker function