function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
CALL STACK EXTERNAL API
CALLBACK QUEUE
Slide 31
Slide 31 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
log('Start')
CALL STACK EXTERNAL API
CALLBACK QUEUE
Slide 32
Slide 32 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
CALLBACK QUEUE
setTimeout(...)
Slide 33
Slide 33 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
100ms timer
CALLBACK QUEUE
Slide 34
Slide 34 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
100ms timer
log(2)
CALLBACK QUEUE
Slide 35
Slide 35 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
log('Callback')
CALLBACK QUEUE
Slide 36
Slide 36 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
log
('Callback')
CALLBACK QUEUE
Slide 37
Slide 37 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
CALLBACK QUEUE
log
('Callback')
log('End')
Slide 38
Slide 38 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
log('Callback')
CALL STACK EXTERNAL API
CALLBACK QUEUE
Slide 39
Slide 39 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
CALL STACK EXTERNAL API
CONSOLE OUTPUT
Start
2
End
Callback
Slide 40
Slide 40 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 0);
let sum = 1 + 1;
console.log(sum);
console.log('End');
}
EVENT LOOP
CALL STACK EXTERNAL API
CONSOLE OUTPUT
Start
2
End
Callback
Slide 41
Slide 41 text
No content
Slide 42
Slide 42 text
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let result = blockingCode();
console.log(result);
console.log('End');
}
EVENT LOOP
demo()
CALL STACK EXTERNAL API
100ms timer
blockingCode()
CALLBACK QUEUE
Slide 43
Slide 43 text
EVENT LOOP
demo()
CALL STACK EXTERNAL API
blockingCode()
CALLBACK QUEUE
this blocks
callback execution
log
('Callback')
function demo() {
console.log('Start')
setTimeout(() => {
console.log('Callback');
}, 100);
let result = blockingCode();
console.log(result);
console.log('End');
}
Slide 44
Slide 44 text
demo
Slide 45
Slide 45 text
web workers
Slide 46
Slide 46 text
new Worker()
Slide 47
Slide 47 text
No content
Slide 48
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postMessage()
Slide 49
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onmessage
Slide 50
Slide 50 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 51
Slide 51 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 52
Slide 52 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 53
Slide 53 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 54
Slide 54 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 55
Slide 55 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 56
Slide 56 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 57
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Main says: Talk to me. // printed by worker
Worker says: Here I am. // printed by main thread
CONSOLE OUTPUT
Slide 58
Slide 58 text
use cases
PREFETCHING DATA
CALCULATIONS
SPELL CHECK
MASSIVE DATA
IMAGE PROCESSING
Slide 59
Slide 59 text
considerations
Slide 60
Slide 60 text
cleanup
Slide 61
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close()
Slide 62
Slide 62 text
worker.terminate()
Slide 63
Slide 63 text
let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
close();
};
WORKER.JS
Slide 64
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let w = new Worker(worker.js);
w.onmessage = (e) => {
console.log(
`Worker says: ${e.data}`
);
};
w.postMessage('Talk to me.');
w.terminate();
MAIN.JS
onmessage = (e) => {
console.log(
`Main says: ${e.data}`
);
postMessage('Here I am.')
};
WORKER.JS
Slide 65
Slide 65 text
No content
Slide 66
Slide 66 text
am i closed?
Slide 67
Slide 67 text
No content
Slide 68
Slide 68 text
No content
Slide 69
Slide 69 text
pick up after yourself
Slide 70
Slide 70 text
access
limitations
DOM
GLOBAL SCOPE
PARENT FUNCTIONS
WINDOW
Slide 71
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communication
Slide 72
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sharing data
Slide 73
Slide 73 text
sharing data
Slide 74
Slide 74 text
copying
sharing
data
Slide 75
Slide 75 text
let w = new Worker(worker.js);
let foo = { x: 1, y: 2 };
w.onmessage = (e) => {
console.log(
`My x is: ${foo.x}
Worker x is: ${e.data.x}`
);
};
w.postMessage(foo);
MAIN.JS
let foo;
onmessage = (e) => {
foo = e.data;
foo.x = 42;
postMessage(foo)
};
WORKER.JS
Slide 76
Slide 76 text
let w = new Worker(worker.js);
let foo = { x: 1, y: 2 };
w.onmessage = (e) => {
console.log(
`My x is: ${foo.x}
Worker x is: ${e.data.x}`
);
};
w.postMessage(foo);
MAIN.JS
let foo;
onmessage = (e) => {
foo = e.data;
foo.x = 42;
postMessage(foo)
};
WORKER.JS
Slide 77
Slide 77 text
let w = new Worker(worker.js);
let foo = { x: 1, y: 2 };
w.onmessage = (e) => {
console.log(
`My x is: ${foo.x}
Worker x is: ${e.data.x}`
);
};
w.postMessage(foo);
MAIN.JS
let foo;
onmessage = (e) => {
foo = e.data;
foo.x = 42;
postMessage(foo)
};
WORKER.JS
Slide 78
Slide 78 text
let w = new Worker(worker.js);
let foo = { x: 1, y: 2 };
w.onmessage = (e) => {
console.log(
`My x is: ${foo.x}
Worker x is: ${e.data.x}`
);
};
w.postMessage(foo);
MAIN.JS
let foo;
onmessage = (e) => {
foo = e.data;
foo.x = 42;
postMessage(foo)
};
WORKER.JS
Slide 79
Slide 79 text
My x is: 1 // original object literal
Worker x is: 42 // modified by worker code
CONSOLE OUTPUT
Slide 80
Slide 80 text
structured clone algorithm
Slide 81
Slide 81 text
excludes
ERROR & FUNCTION
DOM NODES
PROTOTYPE CHAIN
DESCRIPTORS
Slide 82
Slide 82 text
transferring
sharing
data
Slide 83
Slide 83 text
postMessage(foo, [trans])
Slide 84
Slide 84 text
let arrBuff = new ArrayBuffer(1024)
let foo = {
key: 'foo_buffer',
buffer: arrBuff
};
let w = new Worker(worker.js);
w.postMessage(foo, [arrBuff]);
MAIN.JS
Slide 85
Slide 85 text
let arrBuff = new ArrayBuffer(1024)
let foo = {
key: 'foo_buffer',
buffer: arrBuff
};
let w = new Worker(worker.js);
w.postMessage(foo, [arrBuff]);
MAIN.JS
Slide 86
Slide 86 text
benefits MUCH FASTER
LESS MEMORY
Slide 87
Slide 87 text
drawbacks ARRAY BUFFERS
IMAGE BITMAPS
Slide 88
Slide 88 text
drawbacks ONE THREAD
AT A TIME
Slide 89
Slide 89 text
broadcast channels
Slide 90
Slide 90 text
shared browser context
Slide 91
Slide 91 text
// could be any executing context
let channel = new BroadcastChannel("foo");
// listens to message on channel 'foo' from anyone
foo.onmessage = (e) => console.log(e.data);
// posts message to anyone who is listening to 'foo'
foo.postMesage('Is there anybody out there?');
MAIN.JS / WORKER.JS
Slide 92
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// could be any executing context
let channel = new BroadcastChannel("foo");
// listens to message on channel 'foo' from anyone
foo.onmessage = (e) => console.log(e.data);
// posts message to anyone who is listening to 'foo'
foo.postMesage('Is there anybody out there?');
MAIN.JS / WORKER.JS
Slide 93
Slide 93 text
No content
Slide 94
Slide 94 text
supports tabs & workers
Slide 95
Slide 95 text
same origin
Slide 96
Slide 96 text
e.data still a copy
Slide 97
Slide 97 text
shared memory
Slide 98
Slide 98 text
No content
Slide 99
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SharedArrayBuffer
Slide 100
Slide 100 text
// set aside 1KB of shared memory
let sab = new SharedArrayBuffer(1024);
// create a view on the shared memory with 256 Int32
let intArray = new Int32Array(sab);
let w = new Worker(worker.js);
w.postMessage(intArray);
MAIN.JS
Slide 101
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// set aside 1KB of shared memory
let sab = new SharedArrayBuffer(1024);
// create a view on the shared memory with 256 Int32
let intArray = new Int32Array(sab);
let w = new Worker(worker.js);
w.postMessage(intArray);
MAIN.JS
Slide 102
Slide 102 text
// set aside 1KB of shared memory
let sab = new SharedArrayBuffer(1024);
// create a view on the shared memory with 256 Int32
let intArray = new Int32Array(sab);
let w = new Worker(worker.js);
w.postMessage(intArray);
MAIN.JS
Slide 103
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let workerIntArray;
onmessage = (e) => {
// same instance accessing the same memory
workerIntArray = e.data;
Atomics.store(workerIntArray, 42, 500);
};
WORKER.JS