Nine console command Debug JS

The following nine console commands can help us to debug more easily

• Commonly used console commands, the most common thing Console.log ()

1     // Common console commands, of which the most commonly used Console.log ()2     console.log ();  3 Console.info (' Some information ');  4 console.error (' error ');  5 Console.warn (' warn '        

• Console.dir () Viewing the properties and methods of an object

1     // View information about the object 2     var objinfo={3 name: ' lazy ',4 age:20,5 sex: ' Male '  }; 7 console.dir (objinfo);           

• Console.trace () traces the call path of a function, needs to know how a function is called, and adds console.trance () to it.

1//Tracing the call path of a function2functionAdd (a, b) {3Console.trace (); 4 return a+b; 5 } 6 var x=add2 (1,1< Span style= "color: #000000;" >);  7 function add1 (a, B) { Span style= "color: #008080;" > 8 return add (a, b)  9 Span style= "color: #000000;" >}10 function add2 (a, b {11 return add1 (a, b); 12}             

• Console.time () console.timeend () shows a part of the program run time

1     // chronograph function 2     console.time (' console Timer ");  for (var i=0;i<100;i++) { }6 console.timeend (' Console timer ");       

• Console.profile (name) Console.profileend (name) The run time of each part of the parser

1//Performance analysis, analysis of the running time of various parts of the program, identify bottlenecks2functionAll () {3Forvar i=0;i<10;i++){4 FUNC01 (10);5}6 FUNC02 (100);7}8functionFUNC01 (count) {9Forvar i=0;i<count;i++){Ten  -one}   -function func02 (count) {+ for (var i=0;i<count;i++) {  console.profile} (' Performance Analyzer ');  All ();  Console.profileend (' Performance Analyzer ');               

• Console.group () console.groupend () is displayed in group form

1     // Information Group 2     console.group (' First Group ');  3 Console.log (' First article ');  4 Console.log (' Second article '); console.groupend ();  6 Console.group (' Second group ');  7 Console.log (' First article ');  8 Console.log (' Second article ');  9 console.groupend ();               

• Console.dirxml () Displays the contents of a node

1     // Display the contents of a node 2     var mynode=document.getelementbyid (' sp-float ');  3 console.dirxml (mynode);     

• Support placeholders

1     // placeholder that supports printf placeholder Format,%s,%d,%i,%f,%o2     console.log ('%d%d months ', 2016,8,10);  

• Console.assert () to determine if a variable is true

1     // Determine if a variable is true (if the result is false, output the appropriate information in the console and throw an Error)2     console.assert (true==0);   

Nine console command Debug JS