I stepped on a foundation pit today

introduction

I wonder if you have such an experience ： It's wrong to suddenly find out that you have a deep-rooted view for a long time ？

I stepped on a pit today ： I always remember in my impression setInterval After definition, it will Execute now Once inside the logic , So when implementing the logic in the figure below , I will take the second step （” Execute the logic immediately a“） It's not necessary , This province has brought me a bug, Khan, ~

It's out bug, We need to remedy , Don't lose your attitude ！

Bronze grade

Speaking of the simplest fix , That's the method we often use , The code is as follows ：

function fun(){}
fun();
setInterval(fun, 1000);

Yes , It's so simple and plain ！

Diamond grade

Since it's diamond grade , Then you have to play some tricks , Otherwise, it will be useless .

In fact, there is a hidden danger in the above bronze level implementation ： It cannot be ensured that there is only one timer executing this logic at the same time . Then let's encapsulate ：

let timer = null;
function func(){}
function mainFun(callback, time){
    callback();
    return setInterval(callback, time);
}
timer && clearInterval(timer);
timer = mainFun(func, 1000);

Xingyao class

Use the objective function to return the objective function itself .

let timer = null;
function func(){}
timer && clearInterval(timer);
timer = mainFun(func(), 1000);

Um. , The code style is a little higher .

King level

Since it needs to be executed immediately , Then why not use self executing functions ？

let timer = null;
timer && clearInterval(timer)
timer = setInterval((function func () {})(), 1000);

Although the logic is the same as above , But I don't know why it's a little tall ,^-^

Conclusion

In fact, I still don't understand why I have such a wrong memory , And no correction has been found for so long .

It's not terrible to make mistakes , The terrible thing is that you don't realize you've made a mistake ！

It takes a good blacksmith to make steel. , Don't look at how big others' implementation methods are , In fact, it is the result of some reasonable combination of basic knowledge , As long as you have a good foundation , Even in the face of a simple piece of code, you can play a different trick ！

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~ The end of this paper , Thank you for reading ！

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Learn interesting knowledge , Make interesting friends , Create interesting souls ！

Hello everyone , I am a 〖 The samadhi of programming 〗 The author of Hermit King , My official account is 『 The samadhi of programming 』, Welcome to your attention , I hope you can give me more advice ！