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| function query(label) { | |
| console.log(`(${label}) created 'lazy promise', but not started yet`); | |
| return { | |
| then(r) { | |
| console.log(`(${label}) started!`); | |
| // ... process query | |
| // "return" them: | |
| r([{ data: `result for ${label}` }]); | |
| }, | |
| }; | |
| } | |
| // won't execute, it's lazy: | |
| query(1); | |
| console.log(); | |
| // will execute: | |
| const results = await query(2); | |
| console.log("(2) got results:", results); | |
| console.log(); | |
| // will also execute: | |
| query(3).then((results) => { | |
| console.log("(3) got results:", results); | |
| }); | |
| // program output: | |
| // | |
| // (1) created 'lazy promise', but not started yet | |
| // | |
| // (2) created 'lazy promise', but not started yet | |
| // (2) started! | |
| // (2) got results: [ { data: 'result for 2' } ] | |
| // | |
| // (3) created 'lazy promise', but not started yet | |
| // (3) started! | |
| // (3) got results: [ { data: 'result for 3' } ] |
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