indexof in javascript object code example

Example 1: javascript indexOf object value in array

// Get index of object with specific value in array
const needle = 3; // needle
const haystack = [{ id: 1 }, { id: 2 }, { id: 3 }]; // haystack
const index = haystack.findIndex(item => item.id === needle);

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: indexof javascript

arr.indexOf(searchElement[, fromIndex])

Example 4: indexof javascript

var str = "Please locate where 'locate' occurs!";

var ind1 = str.indexOf("locate"); // return location of first value which founded
var ind2 = str.lastIndexOf("locate"); // return location of last value which founded
var ind3 = str.indexOf("locate", 15); // start search from location 15 and then take first value which founded
var ind4 = str.search("locate");
//The search() method cannot take a second start position argument. 
//The indexOf() method cannot take powerful search values (regular expressions).

document.write("<br>" + "Length of string:", len);
document.write("<br>" + "indexOf:", ind1);
document.write("<br>" + "index of last:", ind2);
document.write("<br>" + "indexOf with start point:", ind3);
document.write("<br>" + "search:", ind4);