javascript string findindex code example

Example 1: javascript findindex

const array1 = [5, 12, 8, 130, 44];
const search = element => element > 13;
console.log(array1.findIndex(search));
// expected output: 3

const array2 = [
  { id: 1, dev: false },
  { id: 2, dev: false },
  { id: 3, dev: true }
];
const search = obj => obj.dev === true;
console.log(array2.findIndex(search));
// expected output: 2

Example 2: javascript indexof

//indexOf getting index of array element, returns -1 if not found
var colors=["red","green","blue"];
var pos=colors.indexOf("blue");//2

//indexOf getting index of sub string, returns -1 if not found
var str = "We got a poop cleanup on isle 4.";
var strPos = str.indexOf("poop");//9

Example 3: findindex js

// 	findIndex(callback fn)  

//	.... return index (when condition meets)
//  .... return -1 (if condition not meets)

const array = [5, 12, 8, 130, 44];

/// it returns the index of number which satisfy the condition true
const index = array.findIndex((item)=> item>10);   //1

/// now we can check what element at that index...
console.log(array[index]); // array[1]

Example 4: js indexof string

const paragraph = 'The quick brown fox';

console.log(paragraph.indexOf('T'));
>> 0

console.log(paragraph.indexOf('h'));
>> 1

console.log(paragraph.indexOf('Th'));
>> 0

console.log(paragraph.indexOf('he'));
>> 1

console.log(paragraph.indexOf('x'));
>> 18

Example 5: make indexOF in js

function indexOf(arr, value) {
  for (let [i, e] of arr.entries()) {
    if (value == e) return i;
  }
  return -1;
}
indexOf([1,2,3], 2);                     //returns 1

Example 6: js indexof string

str.indexOf(searchValue[, fromIndex])