JavaScript techniques for intercepting and cutting strings_javascript techniques

The cutting and interception of strings may not be used very often, and the points are relatively fine, so prepare and check on your own. Be prepared.

Since everything was tested in a demo before, please forgive me if there is any typo. Some other properties will be added later.

1. Function: split()

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

Example: str="jpg|bmp|gif|ico|png"; arr=str.split("|");
//arr is an array containing the character values ​​"jpg", "bmp", "gif", "ico" and "png"

2. Function: join()

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(”|”);
//The result is jpg|bmp|gif|ico|png

3. Function: concat()

Function: Connect two arrays together;

Example: arr1=[1,2,3,4]
arr2=[5,6,7,8]
alert(arr1.concat(arr2)) //The result is [1,2,3,4,5,6,7,8]

4. Function: charAt()

Function: Return the character at the specified position. The index of the first character in the string is 0. If the parameter index is not between 0 and string.length, this method returns an empty string.

Example: var str='a,g,i,d,o,v,w,d,k,p'
alert(str.charAt(2)) //The result is g

5: Function: charCodeAt()

Function: The charCodeAt() method returns the Unicode encoding of the character at the specified position. This return value is an integer between 0 - 65535.

The methods charCodeAt() and charAt() methods perform similar operations, except that the former returns the encoding of the character at the specified position, while the latter returns a character substring.

Example: var str='a,g,i,d,o,v,w,d,k,p'
alert(str.charCodeAt(2)) //The result is 103. That is, the Unicode encoding of g is 103

6. Function: slice()

Function: arrayObject.slice(start,end)

start: required. Specifies where to start the selection. If negative, it specifies the position from the end of the array. That is, -1 refers to the last element, -2 refers to the second to last element, and so on.

End: optional. Specifies where the selection ends. This parameter is the array index at the end of the array fragment. If this parameter is not specified, the split array contains all elements from start to the end of the array. If this parameter is negative, it specifies the elements starting from the end of the array.

Returns a new array containing the elements in arrayobject from start to end (excluding this element).

Example: var str='ahji3o3s4e6p8a0sdewqdasj'
alert(str.slice(2,5)) //result ji3

7. Function: substring()

Definition and Usage The substring method is used to extract characters between two specified subscripts in a string.

Syntax stringObject.substring(start,stop)

start required. A nonnegative integer that specifies the position in stringObject of the first character of the substring to be extracted.

stop optional. A nonnegative integer that is one position in the stringObject that is one more than the last character of the substring to be extracted.

If this parameter is omitted, the returned substring will go to the end of the string.

Returns a new string. The string value contains a substring of stringObject. Its content is all the characters from start to stop-1, and its length is stop minus start. Description The substring returned by the substring method includes the characters at start but does not include the characters at end. If start and end are equal, then this method returns an empty string (that is, a string of length 0). If start is greater than end, the method swaps the two parameters before extracting the substring. If start or end is negative, it is replaced by 0.

Example: var str='ahji3o3s4e6p8a0sdewqdasj'
alert(str.substring(2,6)) //The result is ji3o3

8. Function: substr

Definition and Usage The substr method is used to return a substring of specified length starting from the specified position.

Syntax stringObject.substr(start [, length])

The parameter start is 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 is returned. If this parameter is not specified, the substring will be continued to the end of stringObject.

Example: var str = "0123456789";

　　 alert(str.substring(0));------------"0123456789"
　　 alert(str.substring(5));------------"56789"
　　alert(str.substring(10));-----------""
　　alert(str.substring(12));-----------""
　　alert(str.substring(-5));-----------"0123456789"
　　alert(str.substring(-10));----------"0123456789"
　　alert(str.substring(-12));----------"0123456789"
　　alert(str.substring(0,5));----------"01234"
　　alert(str.substring(0,10));---------"0123456789"
　　alert(str.substring(0,12));---------"0123456789"
　　alert(str.substring(2,0));----------"01"
　　alert(str.substring(2,2));----------""
　　alert(str.substring(2,5));----------"234"
　　alert(str.substring(2,12));---------"23456789"
　　alert(str.substring(2,-2));---------"01"
　　alert(str.substring(-1,5));---------"01234"
　　alert(str.substring(-1,-5));--------""

substr 和 substring方法的区别

<script type="text/javascript"> 
var str = "0123456789";// 
alert(str.substring(0));//------------"0123456789" 
alert(str.substring(5));//------------"56789" 
alert(str.substring(10));//-----------"" 
alert(str.substring(12));//-----------"" 
alert(str.substring(-5));//-----------"0123456789" 
alert(str.substring(-10));//----------"0123456789" 
alert(str.substring(-12));//----------"0123456789" 
alert(str.substring(0,5));//----------"01234" 
alert(str.substring(0,10));//---------"0123456789" 
alert(str.substring(0,12));//---------"0123456789" 
alert(str.substring(2,0));//----------"01" 
alert(str.substring(2,2));//----------"" 
alert(str.substring(2,5));//----------"234" 
alert(str.substring(2,12));//---------"23456789" 
alert(str.substring(2,-2));//---------"01" 
alert(str.substring(-1,5));//---------"01234" 
alert(str.substring(-1,-5));//--------"" 
alert(str.substr(0));//---------------"0123456789" 
alert(str.substr(5));//---------------"56789" 
alert(str.substr(10));//--------------"" 
alert(str.substr(12));//--------------"" 
alert(str.substr(-5));//--------------"0123456789" 
alert(str.substr(-10));//-------------"0123456789" 
alert(str.substr(-12));//-------------"0123456789" 
alert(str.substr(0,5));//-------------"01234" 
alert(str.substr(0,10));//------------"0123456789" 
alert(str.substr(0,12));//------------"0123456789" 
alert(str.substr(2,0));//-------------"" 
alert(str.substr(2,2));//-------------"23" 
alert(str.substr(2,5));//-------------"23456" 
alert(str.substr(2,12));//------------"23456789" 
alert(str.substr(2,-2));//------------"" 
alert(str.substr(-1,5));//------------"01234" 
alert(str.substr(-1,-5));//-----------"" 
</script>