This article describes how to optimize functions written in Javascript.
Applicable functions must meet the following conditions::
Produce fixed results
Multiple calls on the page
Complex or time-consuming
The code and analysis are as follows::
Java code:
Copy codeThe Code is as follows: // a function that generates fixed results and is called multiple times on the page
Function check (){
// Simulate time-consuming operations
Var begin = Date. now (); // added by ECMAScript5. If not, change it to + new Date ();
Var ONE_SECOND = 1000,
Result = false;
While (true ){
If (Date. now ()-begin> = ONE_SECOND ){
Result = true;
Break;
}
}
// Rewrite the function and return the result directly.
Check = function (){
Return result;
}
Return result;
}
Var firstBegin = Date. now ();
Check (); // call the nth Function
Var firstEnd = Date. now ();
Check (); // second-level function call
Var secondEnd = Date. now ();
Console. log ("Time consumed by the nth function:" + (firstEnd-firstBegin) + "ms .");
Console. log ("second quadratic function time-consuming:" + (secondEnd-firstEnd) + "ms .");
The result is as follows::
