Several values in JavaScript that can be converted to false

1, [0,nan, "", null,undefined] can be converted directly to false, but these values are not exactly equal

1     vararr = [0, "",false,NULL, Undefined,nan]2      for(vari=0;i<arr.length;i++){3          for(varj=i;j<arr.length;j++){4             if(arr[i]==Arr[j]) {5Console.log (arr[i]+ "=" +arr[j]);6             }7         }8         if(arr[i]!==Arr[i]) {9Console.log (arr[i]+ "! =" +arr[i]);Ten         } One}

2. Variable declaration method

　Defines multiple variables separated by a "," number, where the use of property values inside an object is similar to when the object is defined by a literal.

But the variable is assigned the name = "Zhang San";

The object property is assigned the name: "Zhang San";

<script>    var num = 123,        = "Kyle",        //Name This named variable is not recommended for properties of the top-level object windows, and the name data type is always string        true;    Console.log (Num,result,result); </script>

3. If statement does not add curly braces {}

If the condition is met, the code after the if is executed by default. It is recommended to add curly braces

4. How to change the character specified in a string

A simple alternative to regular expression

1     var str = "ADWGWHFAJKTEJSDAAASQ4SAADDDQWESDAAFDF"; 2     Console.log (Str.replace (/aa/g, "-")); 3     Console.log (Str.split ("AA"). Join ("-"));  
Splits a string as "AA" into an array, with "-" concatenated arrays as strings

5, the Math object--math.randon () probability demonstration;

Math.Round () and Math.floor () demo

1     vararr = [0, 1, 2, 3, 4, 5];2     functionRandom (value1,value2,value3,value4,value5) {3          This[1] =value1;4          This[2] =value2;5          This[3] =Value3;6          This[4] =value4;7          This[5] =Value5;8     }9     varo =NewRandom (0,0,0,0,0);Ten     varO1 =NewRandom (0,0,0,0,0); One     varj = 100000; A      for(vari = 0; I < J; i++) { -          for(varKeyincho) { -Math.Round (Math.random () * 5) = = key? o[key]++: {};//Rounding the         } -          for(varKeyinchO1) { -Math.floor (Math.random () * 6) = = key? o1[key]++: {};//is rounded down -         } +     } -Console.log (o, O1);

6. When creating an object, use a pure number as the attribute name considerations

The constructor calls this[numbers from the creation of this[numbers];

Literal creation Number: Call this[number];

Several values in JavaScript that can be converted to false