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Java-based LeetCode algorithm problem solutions, regularly updated

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2693\. Call Function with Custom Context

Medium

Enhance all functions to have the `callPolyfill` method. The method accepts an object `obj` as it's first parameter and any number of additional arguments. The `obj` becomes the `this` context for the function. The additional arguments are passed to the function (that the `callPolyfill` method belongs on).

For example if you had the function:

function tax(price, taxRate) { const totalCost = price \* (1 + taxRate); console.log(\`The cost of ${this.item} is ${totalCost}\`); }

Calling this function like `tax(10, 0.1)` will log `"The cost of undefined is 11"`. This is because the `this` context was not defined.

However, calling the function like `tax.callPolyfill({item: "salad"}, 10, 0.1)` will log `"The cost of salad is 11"`. The `this` context was appropriately set, and the function logged an appropriate output.

Please solve this without using the built-in `Function.call` method.

**Example 1:**

**Input:** 

    fn = function add(b) { 
        return this.a + b; 
    } 

    args = [{"a": 5}, 7]

**Output:** 12

**Explanation:** 

    fn.callPolyfill({"a": 5}, 7); // 12 

callPolyfill sets the "this" context to {"a": 5}. 7 is passed as an argument.

**Example 2:**

**Input:** 

    fn = function tax(price, taxRate) { 
        return \`The cost of the ${this.item} is ${price \* taxRate}\`; 
    } 

    args = [{"item": "burger"}, 10, 1.1]

**Output:** "The cost of the burger is 11"

**Explanation:** callPolyfill sets the "this" context to {"item": "burger"}. 10 and 1.1 are passed as additional arguments.

**Constraints:**

*   `typeof args[0] == 'object' and args[0] != null`
*   `1 <= args.length <= 100`
*   2 <= JSON.stringify(args[0]).length <= 10⁵