Summary of common techniques for JS interception and splitting strings_javascript techniques

The examples in this article describe the common methods of intercepting and splitting strings with JS. Share it with everyone for your reference, the details are as follows:

JS can use substring() or slice() to intercept strings

Function: substring()

Definition: substring(start,end) represents the string from start to end, including the character at the start position but excluding the character at the end position.

Function: String interception, for example, if you want to get "Minidx" from "MinidxSearchEngine", you need to use substring(0,6)

Example:

var src="images/off_1.png";
alert(src.substring(7,10));
//弹出值为：off

Function: substr()

Definition: substr(start,length) means starting from the start position, intercepting a string of length length.

Function: String interception

Example:

var src="images/off_1.png";
alert(src.substr(7,3));
//弹出值为：off

Function: split()

Function: Use a specified delimiter to split and store a string into an array

Example:

str="jpg|bmp|gif|ico|png";
arr=theString.split("|");
//arr是一个包含字符值"jpg"、"bmp"、"gif"、"ico"和"png"的数组

Function: John()

Feature: Combine an array into a string using a delimiter of your choice

Example:

var delimitedString=myArray.join(delimiter);
var myList=new Array("jpg","bmp","gif","ico","png");
var portableList=myList.join("|");
//结果是jpg|bmp|gif|ico|png

Function: indexOf()

Function: Return the subscript of the first character matching the substring in the string

var myString="JavaScript";
var w=myString.indexOf("v");w will be 2
var x=myString.indexOf("S");x will be 4
var y=myString.indexOf("Script");y will also be 4
var z=myString.indexOf("key");z will be -1 

Function: lastIndexOf()

Definition: The lastIndexOf() method returns the first character index value where a certain character or string appears from right to left (opposite of indexOf)

Function: Return the string index value

Example:

var src="images/off_1.png";
alert(src.lastIndexOf('/'));
alert(src.lastIndexOf('g'));
//弹出值依次为：6,15

Supplement: The difference between substr and substring methods

substr method

Returns a substring of the specified length starting at the specified position.

stringvar.substr(start [, length ])

Parameters

stringvar

Required. The string literal or String object from which the substring is to be extracted.

start

Required. The starting position of the desired substring. The first character in the string has index 0.

length

Optional. The number of characters that should be included in the returned substring.

Description

If length is 0 or negative, an empty string will be returned. If this parameter is not specified, the substring will be continued to the end of stringvar.

Example

The following example demonstrates the use of the substr method.

function SubstrDemo(){
  var s, ss;        // 声明变量。
  var s = "The rain in Spain falls mainly in the plain.";
  ss = s.substr(12, 5); // 获取子字符串。
  return(ss);        // 返回 "Spain"。
}

substring method

Returns the substring located at the specified position in the String object.

strVariable.substring(start, end)
"String Literal".substring(start, end)

Parameters

start

Indicates the starting position of the substring, the index starts from 0.

end

Indicates the end position of the substring, the index starts from 0.

Description

The

substring method will return a string containing the substring from start to the end (excluding end ).

The

substring method uses the smaller of start and end as the starting point of the substring. For example, strvar.substring(0, 3) and strvar.substring(3, 0) will return the same substring.

If start or end is NaN or negative, replace it with 0.

The length of the substring is equal to the absolute value of the difference between start and end. For example, in strvar.substring(0, 3) and strvar.substring(3, 0) the length of the substring returned is 3.

Example

The following example demonstrates the use of the substring method.

function SubstringDemo(){
  var ss; // 声明变量。
  var s = "The rain in Spain falls mainly in the plain..";
  ss = s.substring(12, 17); // 取子字符串。
  return(ss); // 返回子字符串。
}

I hope this article will be helpful to everyone in JavaScript programming.