Best practices for scripting

Write efficient scripts using a JavaScript-like language. Follow best practices for naming, variables, and table access.

This guide will walk you through the best practices for writing efficient and reliable scripts in ServiceNow CPQ using a JavaScript-like language. Following these guidelines will help you create maintainable, readable, and well-performing code.

Quick summary

• Place declarations at the top
• Comment thoughtfully
• Indent brackets
• Use descriptive variable names
• Name variables consistently
• Avoid "new"
• Avoid loose equality ("==")
• Use "const" before "let" and "let" over "var"
• Minimize table lookups

Place declarations at the top

Placing variable and function declarations at the top of your script improves readability and prevents unexpected variable hoisting issues.

1 // Declare and initiate at the beginning
2 let firstName = "";
3 let lastName = "";
4 let price = 0;
5 let discount = 0;
6 let fullPrice = 0,
7 const myArray = [];
8 const myMap= {};

Comment thoughtfully

Use comments to explain complex logic, assumptions, or any non-obvious behavior in your code. Avoid redundant comments that merely repeat the code.

Indent brackets

Properly indenting your code improves its visual structure and makes it easier to understand, especially when dealing with nested blocks.

1 // Good
2 if (condition) {
3 // ...
4 if (nestedCondition) {
5 // ...
6 }
7 }
8
9 // Bad
10 if (condition) {
11 // ...
12 if (nestedCondition) {
13 // ...
14 }
15 }

Use descriptive variable names

Choose names that are meaningful and describe the purpose of the variable or function. This makes your code self- documenting and easier for others to understand.

1 //Good
2 let quoteId = cfgRequest.partner.quote.id.value;
3 let lineID = cfgRequest.partner.quote.lineId.value;
4 let currencyISO = cfgRequest.partner.quote.currencyIsoCode.value;
5 let priceBookID = cfgRequest.partner.quote.pricebookId.value;
6
7 if (quoteId != null) {
8 cfgRequest.quoteIDTest.set("value", quoteId);
9 }
10
11 if (lineID != null) {
12 cfgRequest.lineIDTest.set("value", lineID);
13 }
14
15 if (currencyISO != null) {
16 cfgRequest.currencyISOCodeTest.set("value", currencyISO);
17 }
18
19 if (priceBookID != null) {
20 cfgRequest.pricebookIDTest.set("value", priceBookID);
21 }
22
23 //Bad
24 let x1= cfgRequest.partner.quote.id.value;
25 let x2= cfgRequest.partner.quote.lineId.value;
26 let x3= cfgRequest.partner.quote.currencyIsoCode.value;
27 let x4= cfgRequest.partner.quote.pricebookId.value;
28
29 if (x1 != null) {
30 cfgRequest.quoteIDTest.set("value", x1);
31 }
32
33 if (x2 != null) {
34 cfgRequest.lineIDTest.set("value", x2);
35 }
36
37 if (x3 != null) {
38 cfgRequest.currencyISOCodeTest.set("value", x3);
39 }
40
41 if (x4 != null) {
42 cfgRequest.pricebookIDTest.set("value", x4);
43 }

Name variables consistently

Consistent naming conventions enhance code readability and maintainability. Choose either camelCase or snake_case and stick to it. Logik field variable names use camelCase, so most organizations stay with this convention for readability.

1 // camelCase
2 let firstName = "JohnDoe";
3
4 // snake_case
5 let last_name = "Smith";

Avoid the "new" keyword

Using the new keyword can use more resources, lead to memory leaks, and cause unintended behaviors. Instead, use the literal notation for object creation if possible.

• Use " " instead of new String( )
• Use ( ) instead of new Number( )
• Use false instead of new Boolean( )
• Use { } instead of new Map( )
• Use [ ] instead of new Array( )

Avoid loose equality ("==")

The loose equality operator can lead to unexpected type coercion. For accurate comparisons, use the strict equality operator (===).

1 // Good
2 if (count === 5) {
3 // ...
4 }
5
6 // Bad
7 if (count == "5") {
8 // ...
9 }

Use "const" before "let" and "let" over "var"

Choose variable declaration based on scope and mutability requirements. Use const for variables that won't be reassigned and let for variables that will change. var is also acceptable but is a holdover from previous versions of JavaScript.

1 // Using const for unchanging values
2 const TAX_RATE = 0.15;
3
4 // Using let for mutable values
5 let itemCount = 5;

Minimize table lookups

Excessive table queries can impact performance. Minimize queries by fetching necessary data once and storing it in variables.

To learn about best practices while using the lookup function, see Minimizing table queries.

Related concepts

• Create scripts

Related reference

• ServiceNow CPQ scripting language reference