What is indexOf method in JavaScript?

indexOf() The indexOf() method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex .

Can you use indexOf on a string in JavaScript?

The indexOf() returns the index of the first occurrence of a substring in a string, or -1 if the string does not contain the substring. The indexOf() is case-sensitive.

How do I get lastIndexOf in JavaScript?

lastIndexOf() The lastIndexOf() method returns the index within the calling String object of the last occurrence of the specified value, searching backwards from fromIndex . Returns -1 if the value is not found.

How do I return an index from an array?

To find the position of an element in an array, you use the indexOf() method. This method returns the index of the first occurrence the element that you want to find, or -1 if the element is not found.

Does indexOf work with objects?

indexOf() method returns the index of the first matching item in an array (or -1 if it doesn’t exist). var wizards = [‘Gandalf’, ‘Radagast’, ‘Saruman’, ‘Alatar’]; // Returns 1 wizards. indexOf(‘Radagast’); But… that doesn’t work if the array contains objects instead of simple strings or numbers.

What is the difference between findIndex and indexOf?

findIndex – Returns the index of the first element in the array where predicate is true, and -1 otherwise. indexOf – Returns the index of the first occurrence of a value in an array.

How does string indexOf work?

The indexOf() method returns the position of the first occurrence of specified character(s) in a string. Tip: Use the lastIndexOf method to return the position of the last occurrence of specified character(s) in a string.

How do you use last index?

The Java String class lastIndexOf() method returns the last index of the given character value or substring. If it is not found, it returns -1. The index counter starts from zero….Signature.

How do you find the index in Java?

The indexOf() method is used in Java to retrieve the index position at which a particular character or substring appears in another string. You can use a second argument to start your search after a particular index number in the string. If the specified letter or letters cannot be found, indexOf() returns -1.

Why is indexOf returning?

This is documented behaviour. 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. Because arrays are 0 based, returning 0 would mean starting from the first character was matched; 1, the second character, and so on.

What is splice in JavaScript?

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

How to find the substring in JavaScript?

Find substring within a string in JavaScript 1) Using indexOf The indexOf returns the index of a character or string if it present in the original string, otherwise… 2) Using Regular Expression

How to get the length of a string in JavaScript?

How to get the length of a string in JavaScript? To get the length of a string in JavaScript, use the length property. The length property returns the number of characters in a string. You can try to run the following code to learn how to get the length of a string

What is an array index in JavaScript?

Arrays in JavaScript are zero-based. This means that JavaScript starts counting from zero when it indexes an array. In other words, the index value of the first element in the array is “0” and the index value of the second element is “1”, the third element’s index value is “2”, and so on. This is not unusual in computer programming languages.

What does indexOf do?

Definition and Usage. The indexOf() method returns the position of the first occurrence of a specified value in a string.