.indexof in javascript code example

Example 1: 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 2: indexof javascript

//indexOf - JS method to get 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

//Eg with material ui

<Checkbox
   checked={value.indexOf(option) > -1}
   value={option}
/>

Example 3: javascript indexof with condition

a = [
  {prop1:"abc",prop2:"qwe"},
  {prop1:"bnmb",prop2:"yutu"},
  {prop1:"zxvz",prop2:"qwrq"}
];
    
index = a.findIndex(x => x.prop2 ==="yutu");

console.log(index);

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: .index of javascript

let monTableau = ['un', 'deux','trois', 'quatre'] ;
console.log(monTableau.indexOf('trois')) ;