javascript based learning 2

Array

var arr = new Array(2,1,5,6,7,4,9);

var arr2 is the Array = (1,2, "33 is"); // omitted new to create the array

var ARR3 = [1,2, "33 is"]; // to create the array by a constant

Math.random (); // arbitrary number between 0 and 1.

for ( var I in arr) {document.write (arr [I] + "");} // iterate another arr manner. This method than for high cycle efficiency

1. Stack structure:

push () method : From an inlet, from the same port. Features: last out. Function: add elements to the end of the array,

alert(arr);

var aes = arr.push("ee","sdfs");

alert (aes); Return Value: After adding the element length of the array.

pop () method : removing the last element

var An aes = arr.pop, (),;

alert (aes); Return Value: returns the last element just removed.

Queue structure: Also an out of a feed, from the features: FIFO

shift () method , an element is removed from the head of the array

unshift () method , the head insert elements from the array

the concat () ; combined array, the return value, a new array combined, arr.concat (arr2);

Slice () ; cut list, returns the value, new array sheared, slice (1,3); the second and fourth elements removed index,

splice () ; splice (subscript, length, element);

Delete Function : splice (1,1); removing the second length. 1, var AM arr.splice = (1,1); the return value to delete the second element,

Add Function : splice (1,0, "SDF"); splice (1,0, "SDF", "DSF"); Start additive element from the second element

Alternatively Function : splice (1,1, "sdfsd");

the Join () ; break splicing, the splicing element to a string, arr.join ( "+ S"); Return Value Returns a string

Reverse () ; array in reverse order

Sort () ; ascending order, the default is asc ii coding table to sort strings, not sorted according to size,

2. The two-dimensional array

1,2,3,4,5

6,7,8,9,10

　　var arr = [[],[],[],[],[]];
            var count = 0;每个数组中的元素
            var arr = [];
            for(i=0;i<5;i++){var newArr = []
                for(j=0;j<5;j++){newArr.push(++count);}
                arr.push(newArr);
            }
            alert(arr.length);//返回5
            alert(arr[0]);//返回1,2,3,4,5,

            for(i=0;i<arr.length;i++){
                for(j=0;j<=i;j++){document.write(arr[i][j] + "&ensp");}
                document.write(<br />);
            }

Bubble Sort

 　　var arr4 = [9,4,8,6,7,2 ];
             for (I = 0; I <arr4.length; I ++ ) 
            { 
                for (J = 0; J <arr4.length -i -1; J ++ ) 
                { 
                    iF (arr4 [J]> arr4 [J +. 1 ]) whether the two numbers before and after exchange 
                    { 
                        var tmp = arr4 [J]; 
                        arr4 [J] = arr4 [J +. 1 ]; 
                        arr4 [J + 1'd ] = tmp; 
                    } 
                } 
            } 
            Alert (arr4);

Selection Sort

　　var arr4 = [5,6,4,7,3,9];
            for(i = 0;i < arr4.length;i++)
            {
                for(j = i;j < arr4.length  ; j++)
                {
                    if(arr4[j] < arr4[i])
                    {
                        var tmp = arr4[i];
                        arr4[i] = arr4[j];
                        arr4[j] = tmp;
                    }
                }
            }
            alert(arr4);

Variable function scope

　　　　var A = 10 ;
             function Show () { 
                A =. 5 ; 
            } 
            Show (); 
            Alert (A); // returns. 5 

            var A = 10 ;
             function Show (A) { 
                A =. 5 ; 
            } 
            Show (A); 
            Alert (A); // returns 10, released after the end of the parameter function call 

            var ARR = [1,2 ];
             function Show (ARR) arr.push {(3,4- );} 
            Alert (ARR); //Returns 1,2,3,4 array is a complex data type / types of reference data, is not stored in the function is stored in the stack segment, are complex data types of all the reference address

Function strings : document.write must be used in

var STR = "Hello"; str.charAt (2); the subscript returned l. str [1]; it may not be assigned, STR [. 1] = "X"; , only str = "sdf";

Big () ; with a large font,

Blink () ; (IE incompatible) with flashing string

Bold () ; bold

Fixed () ; typewriter text display,

Strike () ; strikethrough

fontcolor();

fontsize();

Link (); Links

sub();下标， document.write("hello".sub());

SUP (); superscript

the charCodeAt (subscript); return asc ii code value

fromCharCode (asc ii code value)

concat();

　　　　var str = "1";
　　　　var str2 = "2";
　　　　var str3 = str.concat(str2);

String search method:

the indexOf () ; the indexOf (substring, start looking subscript) , the return value, the same position of the first occurrence of the string, or not -1

lastIndexOf () ; lastIndexOf (substring); position after the first occurrence of the same string, the return value is not -1

Search () ; regular expression parameter may be, I case insensitive, G represents the global match

var STR = "ABCABCABC"; str.search ( "ABC"); return 3, the regular expression / abc / i, returns 0

String replacement:

Replace () ; Replace (string matching / regular expression, "df"); return value, the replacement string,

replace ( "are", "sdf "); features can only be found to replace the first goal

replace (/ sf / g, " sdf"); replace all of the same string

the substring (); the substring (2,4); taken subscript 2 and 3 do not include 4, the return value, generating a new string

Slice (); Slice (-2); taken last two characters.

Split (); Split (separator, resulting array); returns an array

var STR = "the this IS IT"; var ARR = str.split ( "", 2); length of the two arrays

Conversion string array arr.join ( ""); Returns a string

toLowCase (); all lowercase

toUpperCase (); all uppercase

javascript based learning 2

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