index function in javascript code example

Example 1: if value in list javascript and return index

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

console.log(index);

Example 2: .index of javascript

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