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 .
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.
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.
|1||int lastIndexOf(int ch)||It returns last index position for the given char value|
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.
The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.
What does indexOf do?
Definition and Usage. The indexOf() method returns the position of the first occurrence of a specified value in a string.