---
title: "indexOf"
description: "Searches for the first occurrence of the substring inside of string."
---

# indexOf

> Searches for the first occurrence of the substring inside of string.

**This function is used by Ignition's Expression language.**

## Description
Searches for the first occurrence of the substring inside of string. Returns the index of where substring was found, or -1 if it wasn't found. The first position in the string is position 0.

## Syntax
`indexOf(string, substring)`

- Parameters

    - string **string** - The string to search through.

    - string **substring** - The string to search for.

- Results

    - string - The index where the substring was first found in the string.

## Examples
```python title="Code Snippet"
indexOf("Hamburger", "urge") //returns 4
```
```python title="Code Snippet"
indexOf("Test", "") //returns 0
```
```python title="Code Snippet"
indexOf("Dysfunctional", "fun") //returns 3
```
```python title="Code Snippet"
indexOf("Dysfunctional", "marble") //returns -1
```
```python title="Code Snippet"
indexOf("banana", "n") //returns 2
```