Nine console commands to make JS debugging easier

I. Commands to display information

 <! doctype html>   
The most common is the console.log.
Two: Placeholder
Console The above concentration supports printf placeholder format, supported placeholders are: characters (%s), integers (%d or%i), floating-point numbers (%f), and objects (%o)
<script type= "Text/javascript" > Console.log ("%d%d months%d days", 2011,3,26);</script>
Effect:
Iii. Grouping of information
   <! doctype html>   
Effect:
Iv. Viewing the information of an object
Console.dir () can display all properties and methods of an object.
<script type= "Text/javascript" > var info = {blog: "http://www.ido321.com", qqgr           oup:259280570, Message: "Program enthusiasts welcome you to join"};   Console.dir (info); </script>
Effect:
V. Display the contents of a node
console.dirxml () is used to display the Html/xml code contained in a node of a Web page. 
<! doctype html>   
Effect:
Vi. Judging if the variable is true
Console.assert () is used to determine whether an expression or variable is true. If the result is no, a corresponding message is output in the console and an exception is thrown.
<script type= "Text/javascript" > var result = 1;       　　Console.assert (result);       　　var year = 2014;   Console.assert (Year = = 2018); </script>
1 is a value of 0, is true, and the second is false, displaying an error message on the console
Tracing the call trajectory of the function.
Console.trace () is used to track the call path of a function.
<script type= the "text/javascript" >/* function is called, in which the Console.trace () method is added to the */function add (A, b) {Console.   　　　　Trace ();   　　return a+b;   　　} var x = ADD3 (n);   　　function Add3 (A, b) {return add2 (A, b);}  　　function Add2 (A, b) {return add1 (A, b);}  function Add1 (A, B) {return Add (A, b);} </script>
Console output Information:
Eight, chronograph function
Console.time () and Console.timeend () are used to display the elapsed time of the code.
<script type= "Text/javascript" > Console.time ("console timer one");   for (Var i=0;i<1000;i++) {for (Var j=0;j<1000;j++) {}} console.timeend ("Console timer one"); </script>
Run Time is 38.84ms
Performance analysis of Console.profile ()
 performance analysis (Profiler) is to analyze the running time of each part of the program, to find out the bottleneck, the method used is Console.profile (). 
<script type= "Text/javascript" >        function all () {                alert (one);          for (var i=0;i<10;i++) {                    funca (;    )             }        &NBSP;FUNCB (10000);        }           Function funca (count) {       for (var i=0;i<count;i++) {}       }        FUNCTION&NBSP;FUNCB (count) {        for (var i=0;i<count;i++) {}      }         Console.profile (' Performance Analyzer ');       all ();        console.profileend ();</script>
Description, LZ test, in all () without alert, control bar no output, plus, there is a performance analysis table, temporarily unclear why, if you know, you can comment.

Nine console commands to make JS debugging easier