Asynchronous nature of this.setState in React
Let's say that I have these two calls:
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment
}));
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment + 1
}));
Because setState is asynchronous, how is it guaranteed that the first call to it will execute first?
javascript reactjs asynchronous
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
add a comment |
Let's say that I have these two calls:
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment
}));
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment + 1
}));
Because setState is asynchronous, how is it guaranteed that the first call to it will execute first?
javascript reactjs asynchronous
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
1
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52
add a comment |
Let's say that I have these two calls:
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment
}));
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment + 1
}));
Because setState is asynchronous, how is it guaranteed that the first call to it will execute first?
javascript reactjs asynchronous
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
Let's say that I have these two calls:
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment
}));
this.setState((prevState, props) => ({
counter: prevState.counter + props.increment + 1
}));
Because setState is asynchronous, how is it guaranteed that the first call to it will execute first?
javascript reactjs asynchronous
javascript reactjs asynchronous
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
asked Nov 14 '18 at 3:47
LearningMathLearningMath
373220
373220
1
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52
add a comment |
1
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52
1
1
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52
add a comment |
1 Answer
1
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From the react documentation of setState() states that
setState() enqueues changes to the component state and tells React that this component and its children need to be re-rendered with the updated state. setState() is also asynchronous, and multiple calls during the same cycle may be batched together. For example, if you attempt to increment or add a value to a counter more than once in the same cycle, that will result in the equivalent of:
Object.assign(
previousState,
{counter: previousState.counter + props.increment},
{counter: previousState.counter + props.increment + 1},
...
)
Subsequent calls will override values from previous calls in the same cycle, so the quantity will only be incremented once. If the next state depends on the current state, we recommend using the updater function form, instead:
this.setState((state) => {
return {counter: state.counter + 1};
});
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
add a comment |
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From the react documentation of setState() states that
setState() enqueues changes to the component state and tells React that this component and its children need to be re-rendered with the updated state. setState() is also asynchronous, and multiple calls during the same cycle may be batched together. For example, if you attempt to increment or add a value to a counter more than once in the same cycle, that will result in the equivalent of:
Object.assign(
previousState,
{counter: previousState.counter + props.increment},
{counter: previousState.counter + props.increment + 1},
...
)
Subsequent calls will override values from previous calls in the same cycle, so the quantity will only be incremented once. If the next state depends on the current state, we recommend using the updater function form, instead:
this.setState((state) => {
return {counter: state.counter + 1};
});
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
add a comment |
From the react documentation of setState() states that
setState() enqueues changes to the component state and tells React that this component and its children need to be re-rendered with the updated state. setState() is also asynchronous, and multiple calls during the same cycle may be batched together. For example, if you attempt to increment or add a value to a counter more than once in the same cycle, that will result in the equivalent of:
Object.assign(
previousState,
{counter: previousState.counter + props.increment},
{counter: previousState.counter + props.increment + 1},
...
)
Subsequent calls will override values from previous calls in the same cycle, so the quantity will only be incremented once. If the next state depends on the current state, we recommend using the updater function form, instead:
this.setState((state) => {
return {counter: state.counter + 1};
});
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
add a comment |
From the react documentation of setState() states that
setState() enqueues changes to the component state and tells React that this component and its children need to be re-rendered with the updated state. setState() is also asynchronous, and multiple calls during the same cycle may be batched together. For example, if you attempt to increment or add a value to a counter more than once in the same cycle, that will result in the equivalent of:
Object.assign(
previousState,
{counter: previousState.counter + props.increment},
{counter: previousState.counter + props.increment + 1},
...
)
Subsequent calls will override values from previous calls in the same cycle, so the quantity will only be incremented once. If the next state depends on the current state, we recommend using the updater function form, instead:
this.setState((state) => {
return {counter: state.counter + 1};
});
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
From the react documentation of setState() states that
setState() enqueues changes to the component state and tells React that this component and its children need to be re-rendered with the updated state. setState() is also asynchronous, and multiple calls during the same cycle may be batched together. For example, if you attempt to increment or add a value to a counter more than once in the same cycle, that will result in the equivalent of:
Object.assign(
previousState,
{counter: previousState.counter + props.increment},
{counter: previousState.counter + props.increment + 1},
...
)
Subsequent calls will override values from previous calls in the same cycle, so the quantity will only be incremented once. If the next state depends on the current state, we recommend using the updater function form, instead:
this.setState((state) => {
return {counter: state.counter + 1};
});
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
edited Nov 14 '18 at 8:25
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
answered Nov 14 '18 at 4:06
Samuel J MathewSamuel J Mathew
3,62212229
3,62212229
add a comment |
add a comment |
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1
Just imagine a queue - first in, first out, regardless of the precise timing of each.
– CertainPerformance
Nov 14 '18 at 3:49
But this has to do with the Javascript engine, and nothing to do with React itself, right?
– LearningMath
Nov 14 '18 at 3:51
Well, it's React that's implementing the processing of the queue, so it is up to React's code - it would be quite possible to implement something else yourself that accepted items and resolved them asynchronously, in a random order, rather than in FIFO order (but that would be confusing)
– CertainPerformance
Nov 14 '18 at 3:52