Function fnCall

The fnCall function calls the function with the given thisArg as the this value and with al of the _args provided as it's `arguments.

This is almost identical to fnApply, except that the function arguments are passed to fnCall individually as a list, while with fnApply that are combined into a single array argument.

Normally, when calling a function, the value of this inside the function is the object that the function was accessed on. With fnCall(), you can pass an arbitrary value as the this when calling an existing function, without first attaching the function to the object as a property. This allows you to use methods of one object as generic utility functions.

@since 0.9.8 @group Function

@param fn - The function to be called @param thisArg - The value of this provided for the call to fn. If the function is not in strict mode, null and undefined will be replaced with the global object, and primitive values will be converted to objects. @param _args - The zero or more arguments to be passed to the fn function. @returns The result of calling the function with the specified this value and arguments.

Example

const module1 = {
    prefix: "Hello",
    x: 21,
    getX() {
        return this.x;
    },
    log(value: string) {
        return this.prefix + " " + value + " : " + this.x
    }
};

// The 'this' parameter of 'getX' is bound to 'module'.
module1.getX(); // 21
module1.log("Darkness"); // Hello Darkness : 21

// Create a new function 'boundGetX' with the 'this' parameter bound to 'module'.
let module2 = {
    prefix: "my",
    x: 42
};

// Call the function of module1 with module2 as it's this
fnCall(module1.getX, module2); // 42
fnCall(module1.log, module2, "friend"); // my friend : 42
  • fnCall<F, T>(fn, thisArg, ...argArray): ReturnType<F>

  • The fnCall function calls the function with the given thisArg as the this value and with al of the _args provided as it's `arguments.

    This is almost identical to fnApply, except that the function arguments are passed to fnCall individually as a list, while with fnApply that are combined into a single array argument.

    Normally, when calling a function, the value of this inside the function is the object that the function was accessed on. With fnCall(), you can pass an arbitrary value as the this when calling an existing function, without first attaching the function to the object as a property. This allows you to use methods of one object as generic utility functions.

    @since 0.9.8 @group Function

    @param fn - The function to be called @param thisArg - The value of this provided for the call to fn. If the function is not in strict mode, null and undefined will be replaced with the global object, and primitive values will be converted to objects. @param _args - The zero or more arguments to be passed to the fn function. @returns The result of calling the function with the specified this value and arguments.

    Type Parameters

    • F extends ((...args: any) => any)
    • T

    Parameters

    • fn: F
    • thisArg: T
    • Rest...argArray: any[]

    Returns ReturnType<F>

    Example

    // min / max number in an array
    let max = fnCall(Math.max, null, 21, 42, 84, 168, 7, 3);
    // 168

    let min = fnCall(Math.min, null, 21, 42, 84, 168, 7, 3);
    // 3

    const module1 = {
        prefix: "Hello",
        x: 21,
        getX() {
            return this.x;
        },
        log(value: string) {
            return this.prefix + " " + value + " : " + this.x
        }
    };

    // The 'this' parameter of 'getX' is bound to 'module'.
    module1.getX(); // 21
    module1.log("Darkness"); // Hello Darkness : 21

    // Create a new function 'boundGetX' with the 'this' parameter bound to 'module'.
    let module2 = {
        prefix: "my",
        x: 42
    };

    // Call the function of module1 with module2 as it's this
    fnCall(module1.getX, module2); // 42
    fnCall(module1.log, module2, "friend"); // my friend : 42

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