How to determine whether a value exists in an array in javascript

Question: How to determine whether an array contains a value

Answer:

More than one method to solve this problem. let's see one by one.

First: using while loop

Array.prototype.contains = function(value) {
  var i = this.length;
  while (i--) {
   if (this[i] == value) {
     return true;
   }
  }
return false;
}

myArray = ["Red","Green", "Black", "Orange", "Yellow"]

console.log(myArray.contains("Black"));
console.log(myArray.contains("Blue"));

Output:

true
false

Second: Another way to check, whether the value exists in the array or not. If value exits, it will return 'true' otherwise false.

myArray = ["Red","Green", "Black", "Orange", "Yellow"]
myArray.includes("Green");

Output:

true

Third: This is the easiest way to find the value that exists in the array. We are using 'for loop'. If value exits, it will return 'true' otherwise false.

myArray = ["Red","Green", "Black", "Orange", "Yellow"];

function isValueExists(array, value){   
 for(var i=0; i< array.length;i++){
   if(array[i]==value){
     return true;
   }
 }
 return false;
}

console.log(isValueExists(myArray, 'Black'));
console.log(isValueExists(myArray, 'blue'));

Output:

true
false

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