How to input a variable into a string using Vue.js? Github application

I have a vuejs application that I uploaded to Github that works. However, when I edited it in Github to make a few changes, the program when run won't accept it. For example, I initially programmed the variable this.stoploss into the string and it worked. When I made a change on Github to add other variables like this.upperBand, this.lowerBand, etc, it didn't work when I ran the program. The application outputs a text "${this.upperBand}" instead of the variable. I noticed the "this" isn't highlighted on the change.

Please let me know your thoughts.

Check out image here