|
72 | 72 |
|
73 | 73 | // Calling resolve multiple times
|
74 | 74 |
|
75 |
| -var promise = new Promise(function(resolve, reject) { |
76 |
| - setTimeout(function() { |
77 |
| - resolve('hello world 1'); |
78 |
| - resolve('hello world 2'); |
79 |
| - resolve('hello world 3'); |
80 |
| - resolve('hello world 4'); |
81 |
| - }, 1000); |
82 |
| -}); |
83 |
| - |
84 |
| -promise.then(function success(data) { |
85 |
| - console.log(data); |
86 |
| -}); |
| 75 | +// var promise = new Promise(function(resolve, reject) { |
| 76 | +// setTimeout(function() { |
| 77 | +// resolve('hello world 1'); |
| 78 | +// resolve('hello world 2'); |
| 79 | +// resolve('hello world 3'); |
| 80 | +// resolve('hello world 4'); |
| 81 | +// }, 1000); |
| 82 | +// }); |
| 83 | + |
| 84 | +// promise.then(function success(data) { |
| 85 | +// console.log(data); |
| 86 | +// }); |
| 87 | + |
| 88 | +//promise chain |
| 89 | + |
| 90 | +// function test() { |
| 91 | +// return job().then(function(data) { |
| 92 | +// doSomething(data); |
| 93 | +// }); |
| 94 | +// } |
| 95 | + |
| 96 | +//The pyramid of doom |
| 97 | + |
| 98 | +// function test() { |
| 99 | +// return job() |
| 100 | + |
| 101 | +// .then(function() { |
| 102 | +// return job2(); |
| 103 | +// }) |
| 104 | + |
| 105 | +// .then(function() { |
| 106 | +// return job3(); |
| 107 | +// }) |
| 108 | + |
| 109 | +// .then(function() { |
| 110 | +// return job4(); |
| 111 | +// }) |
| 112 | + |
| 113 | +// .then(function() { |
| 114 | +// doSomething(); |
| 115 | +// }); |
| 116 | +// } |
| 117 | + |
| 118 | +//The ghost promise |
| 119 | + |
| 120 | +// function job() { |
| 121 | +// if (test) { |
| 122 | +// return aNewPromise(); |
| 123 | +// } else { |
| 124 | +// return Promise.resolve(42); // return an anto-resolved promise with `42` in data. |
| 125 | +// } |
| 126 | +// } |
| 127 | + |
| 128 | +//If you want to create an auto-rejected promise, use Promise.reject. |
| 129 | + |
| 130 | +//The forgotten promise |
| 131 | + |
| 132 | +// function test() { |
| 133 | +// var promise = job(); |
| 134 | + |
| 135 | +// return new Promise(function(resolve, reject) { |
| 136 | +// promise.then(function(data) { |
| 137 | +// data = doSomething(data); |
| 138 | +// resolve(data); |
| 139 | +// }, function(error) { |
| 140 | +// reject(error); |
| 141 | +// }); |
| 142 | +// }); |
| 143 | +// } |
| 144 | +//You call a method that returns a promise but you create your own promise: |
| 145 | + |
| 146 | +//Or |
| 147 | + |
| 148 | +// function test() { |
| 149 | +// return job().then(function(data) { |
| 150 | +// return doSomething(data); |
| 151 | +// }); |
| 152 | +// } |
| 153 | + |
| 154 | +//The catch method on a promise is pretty simple because it is an alias for then(null, errorCallback). |
| 155 | + |
| 156 | +//Traps of Catch |
| 157 | + |
| 158 | +// var promise = request(); |
| 159 | + |
| 160 | +// promise.catch(function(error) { |
| 161 | +// displayError(error); |
| 162 | +// }); |
| 163 | + |
| 164 | +// // This is the same code as this: |
| 165 | +// promise.then(null, function(error) { |
| 166 | +// displayError(error); |
| 167 | +// }); |
| 168 | + |
| 169 | +// Example 1 |
| 170 | + |
| 171 | +// let promise = request(); |
| 172 | + |
| 173 | +// promise.then(function(data) { |
| 174 | +// console.log(data); |
| 175 | +// }, function(error) { |
| 176 | +// console.error(error); |
| 177 | +// }); |
| 178 | + |
| 179 | +// Example 2 |
| 180 | + |
| 181 | +// let promise = request(); |
| 182 | + |
| 183 | +// promise |
| 184 | + |
| 185 | +// .then(function(data) { |
| 186 | +// console.log(data); |
| 187 | +// }) |
| 188 | + |
| 189 | +// .catch(function(error) { |
| 190 | +// console.error(data); |
| 191 | +// }); |
| 192 | + |
| 193 | +// To understand how to use then and catch directly, you can think of it as |
| 194 | +// pretty similar to using try { ... } catch { ... }. |
| 195 | +// Let's take the 2 examples and express them in "pseudo-synchronous code" |
| 196 | + |
| 197 | +//Example 1 |
| 198 | + |
| 199 | +// try { |
| 200 | +// let promise = request(); |
| 201 | +// } catch (error) { |
| 202 | +// console.error(error); |
| 203 | +// return; |
| 204 | +// } |
| 205 | +// console.log(data); |
| 206 | + |
| 207 | +// Example 2 |
| 208 | + |
| 209 | +// try { |
| 210 | +// let promise = request(); |
| 211 | +// console.log(data); |
| 212 | +// } catch (error) { |
| 213 | +// console.error(error); |
| 214 | +// } |
| 215 | + |
| 216 | +//Try catch Promise |
| 217 | + |
| 218 | +// function job() { |
| 219 | +// return new Promise(function(resolve, reject) { |
| 220 | +// reject(); |
| 221 | +// }); |
| 222 | +// } |
| 223 | + |
| 224 | +// let promise = job(); |
| 225 | + |
| 226 | +// promise |
| 227 | + |
| 228 | +// .then(function() { |
| 229 | +// console.log('Success 1'); |
| 230 | +// }) |
| 231 | + |
| 232 | +// .then(function() { |
| 233 | +// console.log('Success 2'); |
| 234 | +// }) |
| 235 | + |
| 236 | +// .then(function() { |
| 237 | +// console.log('Success 3'); |
| 238 | +// }) |
| 239 | + |
| 240 | +// .catch(function() { |
| 241 | +// console.log('Error 1'); |
| 242 | +// }) |
| 243 | + |
| 244 | +// .then(function() { |
| 245 | +// console.log('Success 4'); |
| 246 | +// }); |
| 247 | + |
| 248 | +//Another Example |
| 249 | + |
| 250 | +// function job(state) { |
| 251 | +// return new Promise(function(resolve, reject) { |
| 252 | +// if (state) { |
| 253 | +// resolve('success'); |
| 254 | +// } else { |
| 255 | +// reject('error'); |
| 256 | +// } |
| 257 | +// }); |
| 258 | +// } |
| 259 | + |
| 260 | +// let promise = job(true); |
| 261 | + |
| 262 | +// promise |
| 263 | + |
| 264 | +// .then(function(data) { |
| 265 | +// console.log(data); |
| 266 | + |
| 267 | +// return job(false); |
| 268 | +// }) |
| 269 | + |
| 270 | +// .catch(function(error) { |
| 271 | +// console.log(error); |
| 272 | + |
| 273 | +// return 'Error caught'; |
| 274 | +// }) |
| 275 | + |
| 276 | +// .then(function(data) { |
| 277 | +// console.log(data); |
| 278 | + |
| 279 | +// return job(true); |
| 280 | +// }) |
| 281 | + |
| 282 | +// .catch(function(error) { |
| 283 | +// console.log(error); |
| 284 | +// }); |
| 285 | + |
| 286 | +//Another Example |
| 287 | + |
| 288 | +// function job(state) { |
| 289 | +// return new Promise(function (resolve, reject) { |
| 290 | +// if (state) { |
| 291 | +// resolve("success"); |
| 292 | +// } else { |
| 293 | +// reject("error"); |
| 294 | +// } |
| 295 | +// }); |
| 296 | +// } |
| 297 | + |
| 298 | +// let promise = job(true); |
| 299 | + |
| 300 | +// promise |
| 301 | + |
| 302 | +// .then(function (data) { |
| 303 | +// console.log(data); |
| 304 | + |
| 305 | +// return job(true); |
| 306 | +// }) |
| 307 | + |
| 308 | +// .then(function (data) { |
| 309 | +// if (data !== "victory") { |
| 310 | +// throw "Defeat"; |
| 311 | +// } |
| 312 | + |
| 313 | +// return job(true); |
| 314 | +// }) |
| 315 | + |
| 316 | +// .then(function (data) { |
| 317 | +// console.log(data); |
| 318 | +// }) |
| 319 | + |
| 320 | +// .catch(function (error) { |
| 321 | +// console.log(error); |
| 322 | + |
| 323 | +// return job(false); |
| 324 | +// }) |
| 325 | + |
| 326 | +// .then(function (data) { |
| 327 | +// console.log(data); |
| 328 | + |
| 329 | +// return job(true); |
| 330 | +// }) |
| 331 | + |
| 332 | +// .catch(function (error) { |
| 333 | +// console.log(error); |
| 334 | + |
| 335 | +// return "Error caught"; |
| 336 | +// }) |
| 337 | + |
| 338 | +// .then(function (data) { |
| 339 | +// console.log(data); |
| 340 | + |
| 341 | +// return new Error("test"); |
| 342 | +// }) |
| 343 | + |
| 344 | +// .then(function (data) { |
| 345 | +// console.log("Success:", data.message); |
| 346 | +// }) |
| 347 | + |
| 348 | +// .catch(function (data) { |
| 349 | +// console.log("Error:", data.message); |
| 350 | +// }); |
| 351 | + |
| 352 | +//Promise.All , Incase of Multiple Asynchronous tasks have to do with single promise. |
| 353 | + |
| 354 | +// function job(delay) { |
| 355 | +// return new Promise(function(resolve) { |
| 356 | +// setTimeout(function() { |
| 357 | +// console.log('Resolving', delay); |
| 358 | +// resolve('done ' + delay); |
| 359 | +// }, delay); |
| 360 | +// }); |
| 361 | +// } |
| 362 | + |
| 363 | +// var promise = Promise.all([job(1000), job(2000), job(500), job(1500)]); |
| 364 | + |
| 365 | +// promise.then(function(data) { |
| 366 | +// console.log('All done'); |
| 367 | +// data.forEach(function(text) { |
| 368 | +// console.log(text); |
| 369 | +// }); |
| 370 | +// }); |
| 371 | + |
| 372 | +//Promise.race |
| 373 | + |
| 374 | +// function delay(time) { |
| 375 | +// return new Promise(function(resolve) { |
| 376 | +// setTimeout(resolve, time, 'success ' + time); |
| 377 | +// }); |
| 378 | +// } |
| 379 | + |
| 380 | +// Promise.race([delay(500), delay(100)]).then(function(data) { |
| 381 | +// console.log(data); |
| 382 | +// }); |
| 383 | + |
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