new Array()
new Array(len)
new Array([item0,[item1,[item2,...]]]]
Methods to use array objects:
var objArray=new Array();
objArray.concact([item1[,item2[,...]]]-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- and return, the original array is not affected. For example: var arr=["a","b","c"];
arr.concact("d","e");
Will return an array containing the letter elements from "a" to "e". And arr itself is not affected.
objArray.join(separator)------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ )same.
objArray.pop()-------- In layman's terms, it is to pop up the last element of the array. Combined with the following push method, it is possible to use arrays as stacks. The pop method returns the value of the last element of the array and subtracts the length attribute by 1, that is, the last element is lost immediately after returning.
objArray.push([value1[,value2[,...]]]])--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- For example: [1,2,3, 4].push("a","b") will get [1,2,3,4,"a","b"]
objArray.reverse() inverts the elements in the array. For example: [1,2,3].reverse() will get [3,2,1]. This operation is performed on the original array and also returns the array itself.
objArray.shift()------------Remove the first element of the array and return the value of this element. The nature of this method is very similar to the pop method, which is to remove the last element.
objArray.slice(start,end)-------------- Return a subset of the array object. The index starts from start (including start) and ends at the end (excluding end). The original array is not affected. Influence. For example: [1,2,3,4,5,6].slice(1,4) will get [2,3,4]. When start or end is negative, they are used to add the length value. For example: [1,2,3,4,5,6].slice(-4,-1) will get [3,4,5]. If end is less than or equal to start, an empty array will be returned.
objArray.sort(comparefn)---------------------------------------------------------------------------------------------------------------- The function comparefn must accept two parameters element1 and element2. If element1 needs to be ranked before element2, it should return a negative number; if element1 needs to be ranked after element2, it should return a positive number, if two numbers are treated equally (that is, keep the original one ) returns 0. When comparedfn is omitted, the elements are arranged in dictionary order. For example: for the defined comparison function cmp: function cmp(e1,e2){return e1-e2;}, then [3,4,2,7].sort(cmp) will get [2,3,4,7].
objArray.splice(start,deleteCount[,item1,item2[,...]]]]) This is a complex function to complete the delete, substitution and insertion of array elements. Among them, the start parameter indicates the index position to be performed, and deleteCount refers to the number of elements to be deleted from start (including the start position). If deleteCount is omitted, it means that the remaining part of the array to be deleted from start. [,item1[,item2[,...]]]] means an optional list of elements inserted before start. like:
var arr=[0,1,2,3,4,5,6];
arr.splice(1,1);
document.write(arr);//Show "0, 2, 3, 4, 5, 6"
arr=[0,1,2,3,4,5,6];
arr.splice(0,0,"a","b");
document.write(arr);//Show "a,b,0,1,2,3,4,5,6"
arr=[0,1,2,3,4,5,6];
arr.splice(3,2,"c","d");
document.write(arr);//Show "0,1,2,c,d,5,6"
objArray.unshift(item1[,item2[,...]]])------------------------------------------------------------------------------------------------------ Its properties and push method type, but push method is to add elements to the end of the array. For example: [1,2,3,4].unshift("a","b") will get ["a","b",1,2,3,4].
The addition and deletion of js array elements have been confusing. Today I finally found the detailed description. I will give me a code to test it first^-^
var arr = new Array();
arr[0] = "aaa";
arr[1] = "bbb";
arr[2] = "ccc";
//alert(arr.length);//3
arr.pop();
//alert(arr.length);//2
//alert(arr[arr.length-1]);//bbb
arr.pop();
//alert(arr[arr.length-1]);//aaa
//alert(arr.length);//1
var arr2 = new Array();
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
//alert(arr2.length);//2
arr2.pop();
//alert(arr2.length);//1
arr2 = arr2.slice(0,arr2.length-1);
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
arr2[2] = "ccc";
arr2 = arr2.slice(0,1);
alert(arr2.length);//1
alert(arr2[0]);//aaa
alert(arr2[1]);//undefined
shift: Delete the first item of the original array and return the value of the deleted element; if the array is empty, return undefined
var a = [1,2,3,4,5];
var b = a.shift(); //a: [2,3,4,5] b:1
unshift: add the parameter to the beginning of the original array and return the length of the array
var a = [1,2,3,4,5];
var b = a.unshift(-2,-1); //a: [-2,-1,1,2,3,4,5] b:7
Note: The test return value in IE6.0 is always undefined, and the test return value in FF2.0 is 7, so the return value of this method is unreliable. When you need to use the return value, you can use splice instead of this method.
pop: Delete the last item of the original array and return the value of the deleted element; if the array is empty, return undefined
var a = [1,2,3,4,5];
var b = a.pop(); //a: [1,2,3,4] b:5//If you don't need to return, just call it directly
push: Add the parameter to the end of the original array and return the length of the array
var a = [1,2,3,4,5];
var b = a.push(6,7); //a: [1,2,3,4,5,6,7] b:7
concat: Returns a new array, which is composed of adding parameters to the original array.
var a = [1,2,3,4,5];
var b = a.concat(6,7); //a: [1,2,3,4,5] b: [1,2,3,4,5,6,7]
splice(start,deleteCount,val1,val2,...): DeleteCount item from the start position, and insert val1,val2,...
When clearing the array, just pass the startIndex.
If all elements are not deleted, pass the deleteCount parameter.
splice also has the function of deleting first and then adding, that is, delete several elements first, and then add several elements at the deleted position. The number of deleted and added elements must not be equal. At this time, deleteCount is also used.
var a = [1,2,3,4,5];
var b = a.splice(2,2,7,8,9); //a:[1,2,7,8,9,5] b:[3,4]
var b = a.splice(0,1); //Same shift
a.splice(0,0,-2,-1); var b = a.length;//Same unshift
var b = a.splice(a.length-1,1);//Same pop
a.splice(a.length,0,6,7); var b = a.length; //Same push
reverse: Inverse the array
var a = [1,2,3,4,5];
var b = a.reverse(); //a: [5,4,3,2,1] b: [5,4,3,2,1]
sort(orderfunction): sort the array by specified parameters
var a = [1,2,3,4,5];
var b = a.sort(); //a:[1,2,3,4,5] b:[1,2,3,4,5]
slice(start,end): Returns a new array composed of items from the specified start subscript to the end subscript in the original array.
var a = [1,2,3,4,5];
var b = a.slice(2,5); //a: [1,2,3,4,5] b: [3,4,5]
join(separator): group the elements of the array into a string, with separator as the separator, if omitted, use the default comma as the separator
var a = [1,2,3,4,5];
var b = a.join("|"); //a: [1,2,3,4,5] b: "1|2|3|4|5"
Here is another way to use array to simulate javaStringBuffer to process strings:
The code copy is as follows:
/**
* String processing function
*/
function StringBuffer() {
var arr = new Array;
this.append = function(str) {
arr[arr.length] = str;
};
this.toString = function() {
return arr.join("");//Ping the array that appends into a string
};
}
Today, I suddenly discovered that join is a good way to convert arrays into strings in the application, so I encapsulated them into objects and used:
The code copy is as follows:
/**
*Convert arrays into strings that are split by specific symbols
*/
function arrayToString(arr,separator) {
if(!separator) separator = "";// If separator is null, it will be empty by default
return arr.join(separator);
}
/**
* Find the string contained in the array
*/
function arrayFindString(arr,string) {
var str = arr.join("");
return str.indexOf(string);
}