#Delayedtimer

[hvacparts005]

Idec Relays Gt3A-3Af20-Delayed Timer Dpdt | PartsHnC

The IDEC GT3A-3AF20 is a versatile delayed timer relay designed for precise time-delay control in industrial and automation systems. Featuring a DPDT (Double Pole Double Throw) contact configuration, it offers reliable switching for a wide range of applications. This timer supports adjustable delay settings, making it ideal for managing operations such as motor control, lighting, and sequential processes. 

[ailtrahq]

Ethereum Dencun, a hotly anticipated upgrade for the second largest blockchain, might be activated in 2024. The upcoming testing mechanism, Devnet-9, will include two new Ethereum Improvement Proposals (EIPs).Ethereum Dencun mainnet activation might be delayedTim Beiko, chair of the ACDE calls, supposes that the Ethereum Cancun-Deneb (DenCun) upgrade might not be activated in 2023. If developers do not foresee launching Dencun on public testnet before Devconnect in November 2023, the update most likely would be activated in 2024.🚨 According to an Ethereum core developer, the activation of the Dencun mainnet may be delayed and might not occur this year as originally planned, citing the impact of the failed Holesky testnet launch. pic.twitter.com/PSe8o2PQnp— Camel_global (@Camel_global) September 22, 2023 Previously, Beiko had recommended activating Dencun upgrade on the following testnets in the following order: Holesky, Goerli and then, Sepolia.Next Wednesday, on Sept. 27, 2023, Ethereum (ETH) developers are going to launch Devnet-9, a crucial testbed for Q4, 2023, enhancements to Ethereum's (ETH) consensus design. Parithosh Jayanthi, a DevOps Engineer at Ethereum Foundation, said that the consensus team is almost ready to launch Devnet-9. The new network might go live even without all clients being ready, Jayanthi stressed:We can still start the devnet as long as we have at least a couple of clients ready and we can add the rest post [launch].As covered by U.Today previously, Ethereum Dencun is the most anticipated upgrade in 2023. It includes the EIP 4844 and EIP 4788 upgrades crucial for the scaling and privacy of Ethereum (ETH) dApps.Devs give Holesky testnet second tryAlso, Ethereum (ETH) developers discussed the activation of Holesky, a consensus testnet that is designed to replace Goerli. As the first launch of Holesky failed, developers are going to relaunch it on Sept. 28, 2023.On Sept. 15, 2023, Holesky collapsed due to the misconfigiration and some other minor bugs. Ethereum (ETH) core developers have been discussing the Dencun upgrade since April 2023. It is set to lay the ground work for the switch to the sharded design of the largest smart contracts platform. Source

[chilin99999-blog]

[JS] 迴圈與非同步處理

本來想先寫些Array操作的實務經驗，不過有觀眾提到想看非同步(Async)處理。

so...插隊一下好囉。

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寫網頁，透過ajax與server side溝通是非常常見的。

而ajax本身是非同步方法。

因此建構網頁時，非同步方法可說是無所不在。

但...寫個範例，還要架API來call未免太過麻煩..

因此我會用其他方式來模擬API request。

// 以Math.random模擬呼叫API時的時間長短不一。並最後回傳Promise物件。 function HTTP(data) { let delayedTime = Math.floor(Math.random() * 1000 + 1); return new Promise((resolve) => { setTimeout(() => { resolve(data + ' ok'); }, delayedTime); }); }

宣告了個HTTP function，模擬呼叫API。

// 跑個forEach呼叫HTTP，將資料塞進myData後檢查其長度，並顯示處理後的資料。 let array = ['a', 'b', 'c', 'd', 'e']; let myData = []; array.forEach(d => { HTTP(d) .then((result) => { myData.push(result); }); }); console.log(myData.length); // 0 myData.forEach(d => console.log(d)); // Nothing shit happened!

花惹發？

為什麼myData.length是0？

明明就塞進了很多資料啊！！！

這是因為，HTTP是非同步方法。

所以底下的console.log與myData.forEach在HTTP回傳資料前，就先執行了。

那...該怎麼辦呢？

let array = ['a', 'b', 'c', 'd', 'e']; let myData = []; let promises = []; // 注意這個 array.forEach(d => { promises.push( HTTP(d) .then((result) => { myData.push(result); }) ); }); Promise.all(promises) .then(() => { console.log(myData.length); // 5 myData.forEach(d => console.log(d)); // Holly cow! It works! });

宣告個promises的陣列，將每個HTTP回傳的Promise物件塞進去！

然後使用Promise.all，限定當每個promise都resolve後，才執行後續(then)的動作。

這樣，就可以處理好非同步請求帶來的執行順序先後問題囉！

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有觀眾提問，有辦法讓HTTP回傳的資料，按照原本的順序嗎？

其實可以的！不過思維略有不同。

let array = ['a', 'b', 'c', 'd', 'e']; // 改用map方式承接所有Promise，但回傳後先不push儲存 let promises = array.map(HTTP); Promise.all(promises) .then((data) => { console.log(data.length); // 5 data.forEach(d => console.log(d)); // Holly cow! It works in order! });

差異在於，HTTP的每個Promise回來，不做後續動作(then)。

Promise.all等待所有Promise完成(resolve)後，將所有回傳資料用then承接。

由於then的data，會"依序"對應到Promise.all裡的所有Promise，

所以最後的forEach就會按原本的順序執行囉！