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The most common is the console.log.
Second, placeholderConsole 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 years%d months%d days", 2011,3,26); </script>%o,%o are used to output object objects, the normal object object, the two are no different, but the print DOM node is not the same:
Console.log ( '%o '////Console.log ('%o '), Document.body.firstElementChild);The%c placeholder is the most common. When using the%c placeholder, the corresponding argument must be a CSS statement that is used to render the output CSS. There are two common types of output: Text style, picture output.
Third, display the content of a node<!DOCTYPE HTML> <HTML> <Head> <title>Common Console Commands</title> <Metahttp-equiv= "Content-type"content= "text/html; charset=utf-8" /> </Head> <Body> <DivID= "Info"> <H3>My blog: http://www.cnblogs.com/chaoran/</H3> </Div> <Scripttype= "Text/javascript"> varInfo=document.getElementById ('Info'); Console.dirxml (info); </Script> </Body> </HTML>
Iv. 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.
Console.assert asserts the input expression and outputs the appropriate information to the console only if the expression is false.
<script type= "Text/javascript" > var result = 1; Console.assert (result); var 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 path of the functionConsole.trace () is used to track the call path of a function.
<script type= "Text/javascript" > /* */ function add (A, b) {console.trace (); return a+B; var x = add3 (1,1 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:
Six, chronograph functionConsole.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++) {}} Co Nsole.timeend ("console timer one"); </script>Performance analysis (Profiler) is the analysis of the various parts of the running time, to find out the bottleneck, the method used is Console.profile ().
<script type= "Text/javascript" >functionAll () {alert (11); for(vari=0;i<10;i++) {Funca (1000); } FUNCB (10000); } functionFunca (count) { for(vari=0;i<count;i++){} } functionFUNCB (count) { for(vari=0;i<count;i++) {} console.profile (' Performance Analyzer '); All (); Console.profileend ();
}</script>
Reference:
Chrome Console Console Usage
Nine console commands to make JS debugging easier
Make JS debugging Easier-console
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