Created
April 15, 2016 11:58
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Chaining promising so they execute sequentially.
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>Title</title> | |
| </head> | |
| <body> | |
| <script type="text/javascript"> | |
| var getters = []; | |
| function getPromise(k) { | |
| return new Promise(function(resolve, reject) { | |
| setTimeout(function() { | |
| console.log("3." + k); | |
| resolve(k); | |
| }, parseInt(Math.random() * 5000)) | |
| }); | |
| } | |
| function first() { | |
| //console.log("First"); | |
| return 1; | |
| } | |
| function second() { | |
| return new Promise(function(resolve) { | |
| setTimeout(function() { | |
| //console.log("Second"); | |
| resolve(2); | |
| }, parseInt(Math.random() * 5000)) | |
| }); | |
| } | |
| function third() { | |
| //console.log("Third"); | |
| for(var i = 0; i < 5; i++) { | |
| getters.push(getPromise(i)); | |
| } | |
| return Promise.all(getters).then(function(ks) { | |
| return 3; | |
| }); | |
| } | |
| function fourth() { | |
| //console.log("Fourth"); | |
| return 4; | |
| } | |
| function fifth() { | |
| return new Promise(function(resolve) { | |
| setTimeout(function() { | |
| //console.log("Second"); | |
| resolve(5); | |
| }, 5000) | |
| }); | |
| } | |
| var seq = [first, second, third, fourth, fifth]; | |
| var currentIndex = -1; | |
| function next() { | |
| currentIndex++; | |
| if(currentIndex < seq.length) { | |
| var p = seq[currentIndex](); | |
| return Promise.resolve(p).then(function(value) { | |
| console.log(value); | |
| return next(); | |
| }); | |
| } | |
| return "Pipeline done."; | |
| } | |
| next().then(function(v) { | |
| console.log(v); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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