The array or array like object of elements to be searched.
The element to locate in the array.
Optional fromIndex: numberThe index to start the search at. If the index is greater than or equal to the array's length, -1 is returned, which means the array will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the array. Note: if the provided index is negative, the array is still searched from front to back. If the provided index is 0, then the whole array will be searched. Default: 0 (entire array is searched).
The first index of the element in the array; -1 if not found.
const array = [2, 9, 9];
arrIndexOf(array, 2); // 0
arrIndexOf(array, 7); // -1
arrIndexOf(array, 9, 2); // 2
arrIndexOf(array, 2, -1); // -1
arrIndexOf(array, 2, -3); // 0
let indices: number[] = [];
const array = ['a', 'b', 'a', 'c', 'a', 'd'];
const element = 'a';
let idx = arrIndexOf(array, element);
while (idx !== -1) {
indices.push(idx);
idx = arrIndexOf(array, element, idx + 1);
}
console.log(indices);
// [0, 2, 4]
function updateVegetablesCollection (veggies, veggie) {
if (arrIndexOf(veggies, veggie) === -1) {
veggies.push(veggie);
console.log('New veggies collection is : ' + veggies);
} else {
console.log(veggie + ' already exists in the veggies collection.');
}
}
let veggies = ['potato', 'tomato', 'chillies', 'green-pepper'];
updateVegetablesCollection(veggies, 'spinach');
// New veggies collection is : potato,tomato,chillies,green-pepper,spinach
updateVegetablesCollection(veggies, 'spinach');
// spinach already exists in the veggies collection.
// Array Like
let arrayLike = {
length: 3,
0: "potato",
1: "tomato",
2: "chillies",
3: "green-pepper" // Not checked as index is > length
};
arrIndexOf(arrayLike, "potato"); // 0
arrIndexOf(arrayLike, "tomato"); // 1
arrIndexOf(arrayLike, "chillies"); 2
arrIndexOf(arrayLike, "green-pepper"); // -1
The arrIndexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.
arrIndexOf()compares searchElement to elements of the Array using strict equality (the same method used by the === or triple-equals operator).