Objective-C

Call a JavaScript Function Passing an Object Argument

See more JavaScript Examples

Demonstrates how to call a JavaScript function with an argument that is an object. Objective-C

#import <CkoStringBuilder.h>
#import <CkoJs.h>
#import <CkoJsonObject.h>
#import <CkoJsonArray.h>

BOOL success = NO;

// This is the JavaScript function we'll call:

// function describeCar(car) {
// 	console.log(`This is a ${car.year} ${car.make} ${car.model}.`);
// }

CkoStringBuilder *sbScript = [[CkoStringBuilder alloc] init];
[sbScript Append: @"function describeCar(car) { console.log(`This is a ${car.year} ${car.make} ${car.model}.`); }"];

CkoJs *js = [[CkoJs alloc] init];

CkoJsonObject *result = [[CkoJsonObject alloc] init];
result.EmitCompact = NO;

// Call Eval to add the function to the context's global object
success = [js Eval: sbScript result: result];
if (success == NO) {
    // Examine the result for an exception.
    NSLog(@"%@",[result Emit]);

    // Also examine the LastErrorText.
    NSLog(@"%@",js.LastErrorText);
    return;
}

// ------------------------------------------------------------------------------
// Call the function describeCar(car)

CkoJsonObject *funcCall = [[CkoJsonObject alloc] init];
funcCall.EmitCompact = NO;

// Create JSON specifying the function name and arguments
// In this case, there is only 1 argument, and it is an object.

// {
//   "name": "describeCar",
//   "args": [
//     {
//       "make": "Toyota",
//       "model": "Corolla",
//       "year": 2022
//     }
//   ]
// }

[funcCall UpdateString: @"name" value: @"describeCar"];

// Create the JSON object that is the argument.
CkoJsonObject *arg = [[CkoJsonObject alloc] init];
[arg UpdateString: @"make" value: @"Toyota"];
[arg UpdateString: @"model" value: @"Corolla"];
[arg UpdateInt: @"year" value: [NSNumber numberWithInt: 2022]];

// Create the arguments array.
CkoJsonArray *argsArray = [[CkoJsonArray alloc] init];
[argsArray AddObjectCopyAt: [NSNumber numberWithInt: 0] jsonObj: arg];

// Add the "args" array to the funcCall.
[funcCall AppendArrayCopy: @"args" jarr: argsArray];

NSLog(@"%@",[funcCall Emit]);

success = [js CallFunction: funcCall result: result];
if (success == NO) {
    // Examine the result for an exception.
    NSLog(@"%@",[result Emit]);

    // Also examine the LastErrorText.
    NSLog(@"%@",js.LastErrorText);
    return;
}

NSLog(@"%@",[result Emit]);

// The describeCar JavaScript function returns nothing. 
// Therefore, the result is "undefined".

// {
//   "type": "undefined",
//   "value": "undefined"
// }

// However, the function emitted text to the console.

CkoStringBuilder *sbOut = [[CkoStringBuilder alloc] init];
[js ConsoleOutputSb: sbOut];
NSLog(@"%@",[sbOut GetAsString]);

// Output:
// This is a 2022 Toyota Corolla.

// -----------------------------------------------------------
// Note: If the object argument is simple, this is an alternative
// and simpler way of creating the funcCall:

[funcCall Clear];
[funcCall UpdateString: @"name" value: @"describeCar"];
[funcCall UpdateString: @"args[0].make" value: @"Toyota"];
[funcCall UpdateString: @"args[0].model" value: @"Corolla"];
[funcCall UpdateInt: @"args[0].year" value: [NSNumber numberWithInt: 2022]];
NSLog(@"%@",[funcCall Emit]);