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JavaScript - Linear search algorithm

JavaScript Searching Algorithm: Exercise-2 with Solution

Write a JavaScript program to find the first index of a given element in an array using the linear search algorithm.

From Wikipedia -
In computer science, a linear search or sequential search is a method for finding an element within a list. It sequentially checks each element of the list until a match is found or the whole list has been searched.
A linear search runs in at worst linear time and makes at most n comparisons, where n is the length of the list. If each element is equally likely to be searched, then linear search has an average case of (n+1)/2 comparisons, but the average case can be affected if the search probabilities for each element vary. Linear search is rarely practical because other search algorithms and schemes, such as the binary search algorithm and hash tables, allow significantly faster searching for all but short lists.

Test Data:
([1, 2, 3, 4, 5, 6, 7, 8, 9], 3) -> 2
([1, 2, 3, 4, 5, 6, 7, 8, 9], 9) -> 8
([1, 2, 3, 4, 5, 6, 7, 8, 9], 1) -> 0
([1, 2, 3, 4, 5, 6, 7, 8, 9], 0) -> -1

Sample Solution:

JavaScript Code:

const linearSearch = (arr, item) => {
  for (const i in arr) 
  {
    if (arr[i] === item) 
      return +i;
  }
  return -1;
};
const nums = [1, 2, 3, 4, 5, 6, 7, 8, 9]
console.log(linearSearch(nums, 3))
console.log(linearSearch(nums, 9))
console.log(linearSearch(nums, 1))
console.log(linearSearch(nums, 0))

Sample Output:

2
8
0
-1

Flowchart:

Flowchart: JavaScript - Linear search algorithm.

Live Demo:

See the Pen javascript-searching-algorithm-exercise-2 by w3resource (@w3resource) on CodePen.


* To run the code mouse over on Result panel and click on 'RERUN' button.*

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Next: Ternary search algorithm.

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JavaScript: Tips of the Day

function and arguments

const person = {
  name: 'Lydia Hallie',
  hobbies: ['coding'],
};

function addHobby(hobby, hobbies = person.hobbies) {
  hobbies.push(hobby);
  return hobbies;
}

addHobby('running', []);
addHobby('dancing');
addHobby('baking', person.hobbies);

console.log(person.hobbies);

The addHobby function receives two arguments, hobby and hobbies with the default value of the hobbies array on the person object.
First, we invoke the addHobby function, and pass "running" as the value for hobby and an empty array as the value for hobbies. Since we pass an empty array as the value for y, "running" gets added to this empty array.
Then, we invoke the addHobby function, and pass "dancing" as the value for hobby. We didn't pass a value for hobbies, so it gets the default value, the hobbies property on the person object. We push the hobby dancing to the person.hobbies array.
Last, we invoke the addHobby function, and pass "bdaking" as the value for hobby, and the person.hobbies array as the value for hobbies. We push the hobby baking to the person.hobbies array.
After pushing dancing and baking, the value of person.hobbies is ["coding", "dancing", "baking"]

Ref: https://bit.ly/2Hcpkm6