Created
September 14, 2017 08:23
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Custom exception creation and usage in JavaScript
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| // From http://eloquentjavascript.net/08_error.html | |
| // Error definition | |
| function InputError(message) { | |
| this.message = message; | |
| this.stack = (new Error()).stack; | |
| } | |
| InputError.prototype = Object.create(Error.prototype); | |
| InputError.prototype.name = "InputError"; | |
| // Code throwing this type of exception | |
| function promptDirection(question) { | |
| var result = prompt(question, ""); | |
| if (result.toLowerCase() == "left") return "L"; | |
| if (result.toLowerCase() == "right") return "R"; | |
| throw new InputError("Invalid direction: " + result); | |
| } | |
| // Handling | |
| for (;;) { | |
| try { | |
| var dir = promptDirection("Where?"); | |
| console.log("You chose ", dir); | |
| break; | |
| } catch (e) { | |
| if (e instanceof InputError) | |
| console.log("Not a valid direction. Try again."); | |
| else | |
| throw e; | |
| } | |
| } |
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