I am a novice. I encountered some doubts when learning the asynchronism of javascript , as follows:
there is an example code like this in teacher Ruan Yifeng"s tutorial:
does not particularly understand the operation mechanism of the whole multi-layer callback. It seems that the parameters passed in will be "remembered" every time setTimeout is executed, but how to understand this code always feels special.
I hope there are seniors who can help with the answer. Thank you
is a callback process
var async = function(arg, callback) {
console.log(`${arg}, `)
setTimeout(function() {
callback(arg * 2)
}, 1000)
}
async(1, function(value){ //1value2
async(value, function(value){ // vaule = 2 value4
async(value, function(value){ // vaule = 4 value8 8
console.log(': ', value)
})
})
})
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