Table of Contents
What is indexOf () in JavaScript?
JavaScript String indexOf() The indexOf() method returns the position of the first occurrence of a value in a string. The indexOf() method returns -1 if the value is not found. The indexOf() method is case sensitive.
What can I use instead of indexOf in JavaScript?
indexOf(v) instead, where ~ is the JavaScript bitwise NOT operator.
What does indexOf return if not found JavaScript?
indexOf() returns 0 — because the substring undefined is found at position 0 in the string undefined .
Does indexOf work with objects?
To find the index of an object in an array, by a specific property: Use the map() method to iterate over the array, returning only the value of the relevant property. Call the indexOf() method on the returned from map array. The indexOf method returns the index of the first occurrence of a value in an array.
Can you use indexOf in an if statement?
Check if a Value Exists Using indexOf() You can use an “if” statement with the indexOf() method to check if a value exists in a string or an array. For example, you could use indexOf() to check if the donut menu contains a particular value. Then, you could print a message to the console if that value is found.
Should I use includes or indexOf?
Update: includes() method uses the SameValueZero algorithm for the comparison. I would suggest using the includes() method to check if the element is present in the array. If you need to know where the element is in the array, you need to use the indexOf() method.
What happens if indexOf does not exist?
indexOf returns the position of an element not if it exists or not. Plus all ( 99% ) programming languages are 0 indexed, or better say strings and arrays are 0 indexed which means that the first element is at position 0.
Why does indexOf return?
The reason it returns -1 instead of “false” is that a needle at the beginning of the string would be at position 0, which is equivalent to false in Javascript. So returning -1 ensures that you know there is not actually a match.
Does indexOf work on arrays?
indexOf() The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.
Is indexOf case sensitive?
The indexOf() method returns the index number where the target string is first found or -1 if the target is not found. Like equals(), the indexOf() method is case-sensitive, so uppercase and lowercase chars are considered to be different.
Is indexOf slow Javascript?
Running indexOf on this array is very slow, making the whole tab freeze for several seconds for each call.
Is indexOf faster?
It seems in large arrays indexOf may be a faster choice. EDIT: Based on more tests, indexOf seems to run faster than a for loop in the version of Safari I’m using (5.0. 3) and slower in just about everything else.
Is not a function at array findIndex?
To solve the “findIndex is not a function” error, make sure to only call the findIndex() method on arrays and in browsers that support it. The findIndex method can only be called on arrays and returns the index of the first element that passes the test. Copied!
What is the difference between indexOf () and charAt () methods?
The char At () method of the string class returns the char value at the specified index. The index Of () method is used to get the integer value of a particular index of String type object.
What is the meaning of indexOf >- 1?
-1 means “no match found”. The reason it returns -1 instead of “false” is that a needle at the beginning of the string would be at position 0, which is equivalent to false in Javascript. So returning -1 ensures that you know there is not actually a match. Follow this answer to receive notifications.