# JavaScript: Missing number from an array

## JavaScript Math: Exercise-83 with Solution

Write a JavaScript program to find the missing number in a given array. There are no duplicates in the list.

Test Data:
([1,2,3,5,6,7]) -> 4
([2,3,4,5]) -> 1

Sample Solution:

JavaScript Code:

``````/**
* Function to find the missing number in an array of consecutive integers.
* @param {number[]} nums - The input array of consecutive integers.
* @returns {number} - The missing number in the array.
*/
function test(nums) {
// Iterate over consecutive integers up to the length of the input array + 1
for (let n = 1; n <= nums.length + 1; n++) {
// Check if the current integer is not found in the input array
if (nums.indexOf(n) === -1)
// If the current integer is not found, return it as the missing number
return n;
}
}

// Test cases
// Assign value to nums
nums = [1, 2, 3, 5, 6, 7];
// Print the value of nums
console.log("nums = " + nums);
// Find the missing number in the said array
console.log("Missing number of the said array: " + test(nums));
// Repeat the above steps for a different value of nums
nums = [2, 3, 4, 5];
console.log("nums = " + nums);
console.log("Missing number of the said array: " + test(nums));
```
```

Output:

```nums = 1,2,3,5,6,7
Missing number of the said array: 4
nums= 2,3,4,5
Missing number of the said array: 1
```

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-83 by w3resource (@w3resource) on CodePen.

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