How to concatenate 2 source fields into 1 target field on a transform map

[Charles Hong]

Hello - i have a transform map importing in data from an excel sheet and i want to take 2 fields from the spreadsheet and concatenate them into one field onto the importing table.I have tried multiple scripts but can't seem to work. Could someone please give me some input on my script below? 

[Harsh Vardhan]

answer is already  a  reserved variable so you don't need to declare it .

answer = (function transformEntry(source) {

// Add your code here

var abc =source.fieldA;

var abc1 = source.fieldB

var op = abc+abc1;
return abc; // return the value to be put into the target field

})(source);

[Charles Hong]

Thank you. 

[Charles Hong]

Last question - when i have "var op = abc+abc1;" there are no spaces in between. How can i do it so there is a space between the 2 values? 

[Charles Hong]

Last question - when i have "var op = abc+abc1;" there are no spaces in between. How can i do it so there is a space between the 2 values?