Web Front-endJS TutorialDo JavaScript's script code blocks belong to macro tasks? What is its execution mechanism and output order?Do JavaScript's script code blocks belong to macro tasks? What is its execution mechanism and output order?
In-depth discussion on the execution mechanism and output order of JavaScript script code blocks
script code block execution mechanism in JavaScript often raises questions about macro tasks and micro tasks, especially when predicting the order of code execution. This article will explore this issue in depth.
script code block: synchronous execution instead of macro task queue
Many materials classify script code blocks as macro tasks, but this is not entirely accurate. The execution of script code blocks is closer to synchronous execution than typical macro tasks. Let's analyze the following code:
console.log('script1');
Promise.resolve().then(() => { console.log('promise1'); });
console.log('script2');
If script code block is considered a macro task, the expected output order should be:
<code>script1 promise1 script2</code>
However, the actual output is:
<code>script1 script2 promise1</code>
The reason is: the browser parser is encountering
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