Some questions about strings

Computer professionals should all know that strings (String type) are inseparable from development in C language, C++, C#, Java, .NET, etc. In web front-end development, strings also have plays an important role, so today’s learning content is: about strings.
1. Search characters
(1) charAt(subscript); Search for the character with the specified subscript, for example: var a="hello" var b=a.charAt(2); Search for the character with subscript 2, the result of b is the first l, Subscripts start from 0
(2) charCodeAt (subscript): Find the ASCII code of the character with the specified subscript, for example: var a=”hyya”; var b=a.charCodeAt(3); Find the ASCII code with subscript 3, which is the character a, and the result is 97
2. Search index by character (subscript)
(1) indexOf ("character"); the index of the first qualified character found from front to back, for example: var a="ayidjds"; var b=indexOf("d"); the result of b is 3 ;
(2) lastindexOf("character"); the index of the first qualified character found from back to front, for example: var a="dfferdrt"; var b=lastindexOf("r"); the result of b is :6;
3. String concatenation
(1) Connect through "+": var str1="hello"; var str2="world"; var str3=str1+str2; the result of str3 is "helloworld";
(2) Connect through concat: var str1=”hello”; var str2=”world”; var str3=str1.concat(str2); the result of str3 is also “helloworld”;
4. Interception of string
(1) slice(star,end); satr: the starting subscript of the interception, end: the end subscript of the interception, where the intercepted part includes the starting position, but does not include the ending position, for example: var a= "hello world"; var b=a.slice(0,4); the result of b is: "hell";
Notice:
a. If the end position is not written, the intercepted part is from the beginning to the end of star, for example: var a="hello world"; var b=a.slice(2); the result of b is: "llo world";
b. If the value of end is less than the value of star, for example: var b.slice(4,2); the return result of b is empty
c. The values ​​of star and end can be negative numbers, which means counting from the back to the front, and the subscripts start from 1
(2) substr(star,count), star is the same as star in slice, count: number, for example: var a="hello world"; var b=a.substr(1,3); the result of b is: "ell";
Notice:
a. If you do not write count, then intercept from star to the end
b.star can also be a negative number, the same as slice
(3) substring(star,end); has the same function as slice
Notice:
a. If the value of end is less than the value of star, the computer will intelligently adjust star and end. For example: substring(4,2) will output the same result as substring(2,4)
b. When star and end are all negative numbers, the output result is empty
c. When either star or end is a negative number, all characters will be intercepted
5. Convert string into array
        split("string");
The knowledge about strings is not limited to these. Students who want to know more about strings can go online to find more detailed information. For me, the above is enough.

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