In this article, we will learn about the indexOf() method in an Object array in Javascript. The indexOf() methods provide the first index at which the given element exists, and -1 in case it is not present in the array.
Syntax:
indexOf(element)indexOf(element, start);
Parameters:
- element: the element to be searched in the input array
- start: the index from which the search has to begin. The default value is set to 0.
Return value:
JavaScript indexOf() method returns the value of the index at which the element is present, and -1 when the element doesn’t exist.
To access the index of the object from the array having a value of an object, we are going to use the JavaScript map method to implement the indexOf() method
JavaScript map() Method:
This method creates a separate array and calls a function for every array element. This method calls the specified function once for every element in the array, maintaining the order.Â
Syntax:
Array.map(function(cValue, ind, Arr), tValue)
Example 1: This example gets the index of val_32 by the map() method.
Javascript
let GFG_Array = [    {        prop_1: "val_11",        prop_2: "val_12",    },    {        prop_1: "val_21",        prop_2: "val_22",    },    {        prop_1: "val_31",        prop_2: "val_32",    },];console.log(JSON.stringify(GFG_Array));Â
function gfg_Run() {    let pos = GFG_Array.map(function (e) {        return e.prop_2;    }).indexOf("val_32");    console.log(        "Index of 'val_32' value object is = " + pos    );}gfg_Run(); |
[{"prop_1":"val_11","prop_2":"val_12"},{"prop_1":"val_21","prop_2":"val_22"},{"prop_1":"val_31","prop_2":"val_32"}]
Index of 'val_32' value object is = 2
Example 2: This example doesn’t get the value so returns the -1 and prints Not Found!
Javascript
// In put array of objectslet GFG_Array = [    {        prop_1: "val_11",        prop_2: "val_12",    },    {        prop_1: "val_21",        prop_2: "val_22",    },    {        prop_1: "val_31",        prop_2: "val_32",    },];// Display Inputconsole.log(JSON.stringify(GFG_Array));Â
// Function to check indexfunction gfg_Run() {    let pos = GFG_Array.map(function (e) {        return e.prop_2;    }).indexOf("val_42");    if (pos == "-1") pos = "Not Found";         // Display output    console.log(        "Index of 'val_42' value object is = " + pos    );}gfg_Run(); |
[{"prop_1":"val_11","prop_2":"val_12"},{"prop_1":"val_21","prop_2":"val_22"},{"prop_1":"val_31","prop_2":"val_32"}]
Index of 'val_42' value object is = Not Found
