Detailed explanation of JS's built-in object String

The built-in objects of JS are mainly divided into four categories: Array String Math Date. This article mainly shares with you the detailed explanation of the built-in object String of JS. I hope it can help you.

String

Mainly introduces the use of some methods:

1. charAt( ) stringObject .charAt(index) Returns the character at the index position in the string

2. charCodeAt( ) stringObject. charCodeAt( index ) Returns the character code at the index position in the string

3. indexOf( ) stringObject.indexOf("Character or string")

Search the given character or string from the string and return its position. If not found, return -1. Only the first occurrence position is detected. Detection from left to right

4. lastIndexOf() stringObject. lastIndexOf("Character or string") Similar to 3, detection from right to left

5. String Interception

a.slice( ) stringObject.slice(start,end) Interception of the string, if the parameter is a negative number, add it to length to get the corresponding position

start: required;

End: Where is the end, it is not included in itself, it can be omitted

# B. Substring () and the parameters are negatively converted to 0, two are both negative at the same time, return null

c. substr( ) stringObject. slice(start,len) Intercept substring

start: is a negative number, add it to length Get the corresponding position

                  len: the intercepted length, if a negative number returns an empty string

[Example question]: Write a JS function to obtain the suffix name of the input parameter. For example, if you enter abc.txt, return .txt

var url="index.txt";
function getFileFormat(url) {
var pos=url.lastIndexOf();
return url.substr(pos);

}
var formatName=getFileFormat(url);

6.split( ) stringObject.split(separator) Split the string into an array and return the array

For example: the string "welcome- to-beijing" Returns the array ["welcome", "to", "beijing"]

##7.replace() stringObject.replace(regexp/substr,replacement)

In Use some characters to replace other characters in a string or replace a substring that matches a regular expression. The return value is a string

regexp: required, the object being replaced

Replacement: required, the replacement value is a string

8. Case conversion

stringObject.toUpperCase() Convert the string to uppercase

stringObject.toLowerCase() Convert the string to lowercase

Related recommendations:

How to implement the interception functions slice(), substring(), substr in js string ()

Detailed explanation of javaScript string tool class StringUtils

Implementation method of converting string to String array in Java

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