JavaScript Memo Review notes 1

One. String manipulation

1. Case

var s = "Hello"= s.touppercase ();" HELLO "g;" HELLO "g.tolowercase ();" Hello

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2. Indexing/Truncation

S.indexof (' o '); 4all.js:1 loading comments ... var l = "Hello World"; undefinedl.substring (0,5);" Hello "l.substring (7);" Orld "

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Two. Arrays

1. Index/length

var NULL true ];undefinedarr.length; 6arr[2]=99; arr;[ NULL true]

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2. Slicing

arr; [nulltrue]arr.slice (1,3); [2, 99]

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3.pop/push and Shift/unshift (remove from scratch, insert from scratch)

 arr;[ 1, 2, 
   
    null , 
    ]arr.pop ();  
    true  
    arr; [ 1, 2, 
    
     null  
     ]arr.push (  1, "SD" 
      7arr;[ 1, 2, 
      
       null 
      , 1, "SD" 
     ]arr.unshift (  ' head ', ' sec ' 
      9arr;[ " Head "," SEC ", 1, 2, 
      
       null 
      , 1," SD "
      " Head "arr;[" SEC ", 1, 2, 
      
       null 
      , 1," SD "] 
    
   

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4. Sort/Flip/Specify Index Delete

 var  arr = [1, 2, 3.14, ' Hello ', null , " Span style= "color: #0000ff;" >true  ];undefinedarr.sort (); [ 1, 2, 3.14, "Hello", null , true  Span style= "color: #000000;" >]arr.reverse (); [ true , null , "Hello", 3.14, 2, 1< Span style= "color: #000000;" >]  var  arr = [' Microsoft ', ' Apple ', ' Yahoo ', ' AOL ', ' Excite ', ' Oracle ' ];undefinedarr.splice ( 2, 3, ' Google ', ' Facebook '  "Yahoo", "AOL", "Excite" ]arr; [ "Microsoft", "Apple", "Google", "Facebook", "Oracle" ]arr.splice ( 2,2< Span style= "color: #000000;" >); [ Google, Facebook] 

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5. Concatenation of arrays

arr; ["Microsoft", "Apple", "Oracle"]var lst = [' A ', ' B ', ' C '];undefinedvar lstadd = Arr.concat (lst); undefinedlstadd; ["Microsoft", "Apple", "Oracle", "A", "B", "C"]lstadd.join ('-');" Microsoft-apple-oracle-a-b-c "

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6. Multidimensional arrays

Three. Objects

var xiaoming = {    ' xiaoming ',    1990,    ' Middle School ',     1.70,    n,    null};undefinedxiaoming.name;" Xiaoming "xiaoming[' name ']; inch xiaoming; true xiaoming.hasownproperty (' name '); true

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Four. Cycle

1. Arrays

var arr = [' Apple ', ' Google ', ' Microsoft '];  for (var i = 0; I <= arr.length; i++) {    alert (arr[i]);}

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2. List

var arr = ' Sdadda ';  for (var i = 0; I <= arr.length; i++) {    alert (arr[i]);}

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3. Objects (Python-like dict)

var o = {    "Jack",    +,    ' Beijing '};  for (var in o) {    alert (O[key]);}

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Five. Map/set (Map: Python-like dict)

1.Map Fetch Value

var New Map ([    [' Michael ',], [' Bob ', ' +], [' Tracy ', ' +]    ]); alert (M.get (' Michael '));

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2.Map Increment/Delete value

var New Map (); M.set (' Alex ',M.set); (' Bob ', ' m ');alert (M.has (' Bob ')); Delete (' Bob '); alert (M.get (' Alex '));

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3.Set (de-newlst, python-like List = Set (LST))

var New Set ([1, 2, 3]); undefineds2; Set {1, 2, 3}s2.add (4); Set {1, 2, 3, 4}s2. Delete (2); true S2; Set {1, 3, 4}all.js:1 loading Comments...s2.add (4); Set {1, 3, 4}

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Six. iterators ( Array , Map and Set all belong iterable to types, with for: of iterations---ps:for. of is against for. In fix)

1.for.. Of

var a = [' A ', ' B ', ' C ']; var New Set ([' A ', ' B ', ' C ']); var New Map ([[1, ' x '],[' name ', ' y '],[3, ' Z ']]);  for (var  X of a) {    alert (x);}  for (var  X of s) {    alert (x);}  for (var  x of m) {    alert (x[0]+ ' = ' +x[1]);}

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2.forEach

//ArrayvarA = [' A ', ' B ', ' C '];a.foreach (function(element, index, array) {//element: A value that points to the current element    //Index: Point to Current index    //array: Points to the array object itselfalert (element);});//Mapvarm =NewMap ([[1, ' X '], [2, ' Y '], [3, ' Z ']]); M.foreach (function(value,key,map) {alert (value); alert (key);});//Set no indexvars =NewSet ([' A ', ' B ', ' C ']); S.foreach (function(element, set) {alert (element);});

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JavaScript Memo Review notes 1