Calculator with Method Chaining
<p>Design a <code>Calculator</code> class. The class should provide the&nbsp;mathematical operations of&nbsp;addition, subtraction, multiplication, division, and exponentiation. It should also allow consecutive operations to be performed using method chaining.&nbsp;The <code>Calculator</code> class constructor should accept a number&nbsp;which serves as the&nbsp;initial value of <code>result</code>.</p>

<p>Your <font face="monospace"><code>Calculator</code>&nbsp;</font>class should have the following methods:</p>

<ul>
	<li><code>add</code> - This method adds the given number <code>value</code> to the&nbsp;<code>result</code> and returns the updated <code>Calculator</code>.</li>
	<li><code>subtract</code> -&nbsp;This method subtracts the given number <code>value</code>&nbsp;from the&nbsp;<code>result</code> and returns the updated <code>Calculator</code>.</li>
	<li><code>multiply</code> -&nbsp;This method multiplies the <code>result</code>&nbsp; by the given number <code>value</code> and returns the updated <code>Calculator</code>.</li>
	<li><code>divide</code> -&nbsp;This method divides the <code>result</code> by the given number <code>value</code> and returns the updated <code>Calculator</code>. If the passed value is <code>0</code>, an error <code>&quot;Division by zero is not allowed&quot;</code> should be thrown.</li>
	<li><code>power</code> -&nbsp;This method raises the&nbsp;<code>result</code> to the power of the given number <code>value</code> and returns the updated <code>Calculator</code>.</li>
	<li><code>getResult</code> -&nbsp;This method returns the <code>result</code>.</li>
</ul>

<p>Solutions within&nbsp;<code>10<sup>-5</sup></code>&nbsp;of the actual result are considered correct.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> 
actions = [&quot;Calculator&quot;, &quot;add&quot;, &quot;subtract&quot;, &quot;getResult&quot;], 
values = [10, 5, 7]
<strong>Output:</strong> 8
<strong>Explanation:</strong> 
new Calculator(10).add(5).subtract(7).getResult() // 10 + 5 - 7 = 8
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> 
actions = [&quot;Calculator&quot;, &quot;multiply&quot;, &quot;power&quot;, &quot;getResult&quot;], 
values = [2, 5, 2]
<strong>Output:</strong> 100
<strong>Explanation:</strong> 
new Calculator(2).multiply(5).power(2).getResult() // (2 * 5) ^ 2 = 100
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> 
actions = [&quot;Calculator&quot;, &quot;divide&quot;, &quot;getResult&quot;], 
values = [20, 0]
<strong>Output:</strong> &quot;Division by zero is not allowed&quot;
<strong>Explanation:</strong> 
new Calculator(20).divide(0).getResult() // 20 / 0 

The error should be thrown because we cannot divide by zero.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>actions</code> is a valid JSON array of strings</li>
	<li><code>values</code>&nbsp;is a valid JSON array of numbers</li>
	<li><code>2 &lt;= actions.length &lt;= 2 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= values.length &lt;= 2 * 10<sup>4</sup>&nbsp;- 1</code></li>
	<li><code>actions[i]</code> is one of &quot;Calculator&quot;, &quot;add&quot;, &quot;subtract&quot;, &quot;multiply&quot;, &quot;divide&quot;, &quot;power&quot;, and&nbsp;&quot;getResult&quot;</li>
	<li>First action is always &quot;Calculator&quot;</li>
	<li>Last action is always &quot;getResult&quot;</li>
</ul>
JavaScript
class Calculator {
    private x: number;

    constructor(value: number) {
        this.x = value;
    }

    add(value: number): Calculator {
        this.x += value;
        return this;
    }

    subtract(value: number): Calculator {
        this.x -= value;
        return this;
    }

    multiply(value: number): Calculator {
        this.x *= value;
        return this;
    }

    divide(value: number): Calculator {
        if (value === 0) {
            throw new Error('Division by zero is not allowed');
        }
        this.x /= value;
        return this;
    }

    power(value: number): Calculator {
        this.x **= value;
        return this;
    }

    getResult(): number {
        return this.x;
    }
}
