seeing that js is written in this way, I don"t know the meaning of the curly braces:
function run(){
{
alert(1);
}
}
I don"t really understand that he just executed a method in curly braces, which has anything to do with the scope of the variable.
the curly braces you have here belong to block scope
ES6 .
Let me talk about another case
such as vue source code rollup
if ('development' !== 'production') {
alert(1)
}after compilation:
{
alert(1)
} ES6 adds block-level scope
variables within the block-level scope cannot be accessed outside the block-level scope. The var declaration does not recognize block-level scope, that is,
{
var a = 1;
}is not a block-level scope, but let,const can recognize a block-level scope
code block, which has two different meanings
es6 , many of the above answers say is used as code segmentation, pure code maintenance requirements, such as two things to do in a function, which are completely unrelated, so that some of the code is not in the main process. For example, you need to record a log and wrap it with {} to make the code easier and easier to read. When combing the process, you do not need to care about this branch task.
{
do something...
}
{
do something...
}
do something... the problem of the landlord is said a lot above, but not so much.
tell me about syntax what means , how to explain and so on.
generate AST directly online and you'll know everything.
in ES6 you can understand curly braces as block-level scope,
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