How to Pass Functions as Parameters in NetSuite SuiteScript

JavaScript allows functions to be treated as first-class citizens, meaning they can be assigned to variables, passed as arguments to other functions, and returned from functions. This capability is highly beneficial in NetSuite SuiteScript for creating flexible and modular code. Consider the following example demonstrating how to pass functions as parameters. This setup allows for dynamic selection of logging mechanisms based on the script's execution context. First, define the functions that will be passed as parameters:

javascript
function f1(text){
    console.log(text);
}

// In a SuiteScript 2.x environment, 'log' would be imported from the 'N/log' module.
function f2(text){
    log.debug({
        title: 'Debug text',
        details: text
    });
}

Next, define a function that accepts another function as a parameter. This 'logger' parameter will be invoked internally by f3.

javascript
function f3(logger){
    //Super complicated logic here
    var a = 1+1;
    logger(a);
    return a;
}

Finally, implement the logic to dynamically select which function to pass to f3 based on the execution context. In SuiteScript 2.x, the N/runtime module is used to determine the context.

javascript
// In a SuiteScript 2.x environment, 'runtime' would be imported from the 'N/runtime' module.
var result;
if (runtime.executionContext === runtime.ContextType.CLIENT) {
    result = f3(f1);
} else {
    result = f3(f2);
}

This approach is also highly effective for setting up callback functions, enabling asynchronous operations or custom event handling.