Introductory example of JavaScript indexOf method (calculates the position where the specified character first appears in the string)_Basic knowledge

JavaScript indexOf method

The indexOf method is used to calculate the first occurrence position of a specified string in the string and return the value. Its syntax is as follows:

Copy code The code is as follows:

str_object.indexOf( search, start )

Parameter description:

参数	说明
str_object	要操作的字符串（对象）
search	必需。要检索的字符串
start	可选。指定开始检索的位置，如省略该参数，则将从字符串的首字符开始检索

Tip: String counting starts from 0.

indexOf method instance

Copy code The code is as follows:

Run this example, output:

Copy code The code is as follows:

3

indexOf is case-sensitive, if the string value to be retrieved does not appear, the method returns -1.