Detailed explanation of javascript built-in object operations_javascript skills

1.indexOf() method -----This method is more commonly used

Returns the position where a specified string value first appears in the string

Using format: stringObject.indexOf(substring, startpos)

For example: Find the seat where the second o is located

var mystr="Hello World!"
document.write(mystr.indexOf("o",mystr.indexOf("o") 1));--------The result is: 7

mystr.indexOf("o") -----The result is 4, start from the table below of the string.

document.write(mystr.indexOf("o",5));Start from the fifth position.

The result is: 7
Note: The .indexOf() method is case-sensitive.
.If the string value to be retrieved does not appear, the method returns -1. ·

2. String split split()

The split() method splits a string into a string array and returns this array.

Syntax:

stringObject.split(separator,limit)

Note: If an empty string ("") is used as a separator, each character in the stringObject will be separated.

For example:

var mystr="86-010-85468578";

Separate the string object mystr

with the character "-"

document.write( mystr.split("-") "
");---Result 86,010,85468578

Split the string object mystr into each character

document.write( mystr.split("") "
");---Result: 8,6,-,0,1,0,-,8,5,4,6 ,8,5,7,8

Split the string object mystr into characters, split 3 times

mystr.split("",3) ------------Result 8,6,-

3. Extract string substring()

The

substring() method is used to extract characters between two specified subscripts in a string.

Syntax:

stringObject.substring(starPos,stopPos)

Note:

1. The returned content is all characters from start (including the character at start position) to stop-1, and its length is stop minus start.

2. If the parameters start and stop are equal, then this method returns an empty string (that is, a string with a length of 0).

3. If start is larger than stop, then this method will exchange these two parameters before extracting the substring.

For example:

var mystr="Hello World!"
document.write( mystr.substring(6) "
");----Intercept all characters with subscripts starting from 6---the result is World!

document.write( mystr.substring(5,4　) );
document.write( mystr.substring(4,5) );------The results are all o and the number of digits taken is 5-4

4. Extract the specified number of characters substr()

The

substr() method extracts the specified number of strings starting from the startPos position from the string.

Syntax:

stringObject.substr(startPos,length)

Note: If the parameter startPos is a negative number, the position starting from the end of the string. That is, -1 refers to the last character in the string, -2 refers to the second to last character, and so on.
If startPos is negative and the absolute value is greater than the string length, startPos is 0

Example: var mystr="Hello World!";
document.write( mystr.substr(6) "
");-----------Intercept World
document.write( mystr.substr(0,5) );----Interception-----Hello

5.Math

Round()

Math.round(x)
The random() method returns a random number between 0 and 1 (greater than or equal to 0 but less than 1).

Math.random();

6.Array array object method

concat() method is used to concatenate two or more arrays. This method returns a new array without changing the original array.

Grammar

arrayObject.concat(array1,array2,...,arrayN)
Note: This method does not modify the existing array, but only returns a copy of the concatenated array.
var myarr1= new Array("010")
var myarr2= new Array("-","84697581");
var mycon=myarr1.concat(myarr2);
document.write(mycon) ---Output 010,-,84697581
The description is just a copy.

The join() method is used to put all elements in the array into a string. Elements are separated by the specified delimiter.

var myarr1= new Array("86","010")
var myarr2= new Array("84697581");
var myarr3= myarr1.concat(myarr2);
document.write(myarr3.join("") "
");------The result is 8601084697581
document.write(myarr3.join("_") "
"); -----The result is: 86_010_84697581

document.write(myarr3.join() "
");-----The result is 86,010,84697581. The default is , separated by sign

7. Reverse the order of array elements reverse()

reverse() method is used to reverse the order of elements in an array.

var myarr1= ["我","爱","你"];
document.write(myarr1.reverse());-----结果是 你,爱,我 注意不是reserve 别写错了

8.选定元素slice()

slice() 方法可从已有的数组中返回选定的元素。

arrayObject.slice(start,end)

1.返回一个新的数组，包含从 start 到 end （不包括该元素）的 arrayObject 中的元素。

2. 该方法并不会修改数组，而是返回一个子数组

var myarr1= ["我","爱","你"];
document.write(myarr1.slice(1,3)) ----结果是-- 爱,你 和substring一样就对了 不过这是针对数组的 其实取出来的个数就是3-1=2

9.数组排序sort()

sort()方法使数组中的元素按照一定的顺序排列。

语法:

arrayObject.sort(方法函数)

1.如果不指定，则按unicode码顺序排列。

2.如果指定，则按所指定的排序方法排序。

function sortNum(a,b) {
return a-b;
}
var myarr = new Array("80","16","50","6","100","1");
document.write(myarr.sort(sortNum)); ---- j结果是：1,6,16,50,80,100

如果是b-a --结果就是100,80,50,16,6,1

以上就是个人总结的一些常用的javascript内置对象的操作，希望大家能够喜欢。