Had a need to parse out full State names from their 2 character abbreviations. This is what I came up with and it appears to work well. The JSON array is from this GitHub repo.
In the form create a new Standard script (text type) and copy the code below into it. Change the record field name to match the one you need to expand into its full name.
//read in the state field from the record set
var StateAbbr = record.fields["State"];
//create JSON array of state abbreviations and names
var states = {
"AL": "Alabama",
"AK": "Alaska",
"AS": "American Samoa",
"AZ": "Arizona",
"AR": "Arkansas",
"CA": "California",
"CO": "Colorado",
"CT": "Connecticut",
"DE": "Delaware",
"DC": "District Of Columbia",
"FM": "Federated States Of Micronesia",
"FL": "Florida",
"GA": "Georgia",
"GU": "Guam",
"HI": "Hawaii",
"ID": "Idaho",
"IL": "Illinois",
"IN": "Indiana",
"IA": "Iowa",
"KS": "Kansas",
"KY": "Kentucky",
"LA": "Louisiana",
"ME": "Maine",
"MH": "Marshall Islands",
"MD": "Maryland",
"MA": "Massachusetts",
"MI": "Michigan",
"MN": "Minnesota",
"MS": "Mississippi",
"MO": "Missouri",
"MT": "Montana",
"NE": "Nebraska",
"NV": "Nevada",
"NH": "New Hampshire",
"NJ": "New Jersey",
"NM": "New Mexico",
"NY": "New York",
"NC": "North Carolina",
"ND": "North Dakota",
"MP": "Northern Mariana Islands",
"OH": "Ohio",
"OK": "Oklahoma",
"OR": "Oregon",
"PW": "Palau",
"PA": "Pennsylvania",
"PR": "Puerto Rico",
"RI": "Rhode Island",
"SC": "South Carolina",
"SD": "South Dakota",
"TN": "Tennessee",
"TX": "Texas",
"UT": "Utah",
"VT": "Vermont",
"VI": "Virgin Islands",
"VA": "Virginia",
"WA": "Washington",
"WV": "West Virginia",
"WI": "Wisconsin",
"WY": "Wyoming"
};
//return full state name based on it's abbreviation
results.html(states[StateAbbr]);
If you’ve got a better way to approach this let me know!