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96 lines
1.6 KiB
Markdown
96 lines
1.6 KiB
Markdown
---
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id: 598e8944f009e646fc236146
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title: Understanding Undefined Value returned from a Function
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challengeType: 1
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forumTopicId: 301177
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dashedName: understanding-undefined-value-returned-from-a-function
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---
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# --description--
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A function can include the `return` statement but it does not have to. In the case that the function doesn't have a `return` statement, when you call it, the function processes the inner code but the returned value is `undefined`.
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**Example**
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```js
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let sum = 0;
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function addSum(num) {
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sum = sum + num;
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}
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addSum(3);
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```
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`addSum` is a function without a `return` statement. The function will change the global `sum` variable but the returned value of the function is `undefined`.
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# --instructions--
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Create a function `addFive` without any arguments. This function adds 5 to the `sum` variable, but its returned value is `undefined`.
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# --hints--
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`addFive` should be a function.
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```js
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assert(typeof addFive === 'function');
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```
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Once both functions have run, the `sum` should be equal to `8`.
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```js
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assert(sum === 8);
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```
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Returned value from `addFive` should be `undefined`.
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```js
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assert(addFive() === undefined);
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```
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Inside the `addFive` function, you should add `5` to the `sum` variable.
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```js
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assert(
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__helpers.removeWhiteSpace(addFive.toString()).match(/sum=sum\+5|sum\+=5/)
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);
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```
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# --seed--
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## --seed-contents--
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```js
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// Setup
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let sum = 0;
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function addThree() {
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sum = sum + 3;
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}
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// Only change code below this line
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// Only change code above this line
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addThree();
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addFive();
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```
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# --solutions--
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```js
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let sum = 0;
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function addThree() {
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sum = sum + 3;
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}
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function addFive() {
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sum = sum + 5;
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}
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addThree();
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addFive();
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```
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