JavaScript functions: Optimizations for generating fixed result functions in JavaScript

Share a JavaScript optimization technique for writing functions.
The applicable function should satisfy the following criteria:
produce a fixed result
Multiple calls on the page
Complex or more time-consuming
Code and analysis are as follows:
A function that produces a fixed result and is called more than once in the page
function Check () {
Simulate time-consuming operations
var begin = Date.now (); ECMAScript5 added, if not supported please change to +new Date ();
var one_second = 1000,
result = false;
while (true) {
if (Date.now ()-Begin >= One_second) {
result = true;
Break
}
}
function overrides, returning directly to the result
Check = function () {
return result;
}
return result;
}
var firstbegin = Date.now ();
Check (); First function call
var firstend = Date.now ();
Check (); Second function call
var secondend = Date.now ();
Console.log ("First function time consuming:" + (Firstend-firstbegin) + "Ms.");
Console.log ("Second function time consuming:" + (Secondend-firstend) + "Ms.");
The results appear as follows:
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