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# Misingi ya JavaScript: Kufanya Maamuzi
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> Sketchnote na [Tomomi Imura](https://twitter.com/girlie_mac)
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## Maswali ya Kabla ya Somo
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[Maswali ya kabla ya somo](https://ff-quizzes.netlify.app/web/quiz/11)
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Kufanya maamuzi na kudhibiti mpangilio wa jinsi msimbo wako unavyoendeshwa hufanya msimbo wako uweze kutumika tena na kuwa imara. Sehemu hii inashughulikia sintaksia ya kudhibiti mtiririko wa data katika JavaScript na umuhimu wake unapotumika na aina ya data ya Boolean.
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[](https://youtube.com/watch?v=SxTp8j-fMMY "Kufanya Maamuzi")
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> 🎥 Bofya picha hapo juu kwa video kuhusu kufanya maamuzi.
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> Unaweza kuchukua somo hili kwenye [Microsoft Learn](https://docs.microsoft.com/learn/modules/web-development-101-if-else/?WT.mc_id=academic-77807-sagibbon)!
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## Muhtasari Mfupi Kuhusu Booleans
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Booleans zinaweza kuwa na thamani mbili tu: `true` au `false`. Booleans husaidia kufanya maamuzi kuhusu mistari gani ya msimbo inapaswa kuendeshwa wakati masharti fulani yanatimizwa.
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Weka Boolean yako kuwa `true` au `false` kama hivi:
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`let myTrueBool = true`
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`let myFalseBool = false`
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✅ Booleans zilipewa jina la George Boole, mtaalamu wa hesabu, falsafa na mantiki wa Kiingereza (1815–1864).
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## Waendeshaji wa Kulinganisha na Booleans
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Waendeshaji hutumika kutathmini masharti kwa kufanya kulinganisha ambako kutazalisha thamani ya Boolean. Hii hapa ni orodha ya waendeshaji wanaotumika mara kwa mara.
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| Alama | Maelezo | Mfano |
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| ------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------ |
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| `<` | **Chini ya**: Inalinganisha thamani mbili na kurudisha aina ya data ya Boolean `true` ikiwa thamani upande wa kushoto ni ndogo kuliko ya kulia | `5 < 6 // true` |
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| `<=` | **Chini au sawa na**: Inalinganisha thamani mbili na kurudisha aina ya data ya Boolean `true` ikiwa thamani upande wa kushoto ni ndogo au sawa na ya kulia | `5 <= 6 // true` |
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| `>` | **Kubwa kuliko**: Inalinganisha thamani mbili na kurudisha aina ya data ya Boolean `true` ikiwa thamani upande wa kushoto ni kubwa kuliko ya kulia | `5 > 6 // false` |
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| `>=` | **Kubwa au sawa na**: Inalinganisha thamani mbili na kurudisha aina ya data ya Boolean `true` ikiwa thamani upande wa kushoto ni kubwa au sawa na ya kulia | `5 >= 6 // false` |
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| `===` | **Usawa mkali**: Inalinganisha thamani mbili na kurudisha aina ya data ya Boolean `true` ikiwa thamani upande wa kulia na kushoto ni sawa NA ni aina sawa | `5 === 6 // false` |
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| `!==` | **Kutokuwepo usawa**: Inalinganisha thamani mbili na kurudisha thamani ya Boolean kinyume na kile ambacho waendeshaji wa usawa mkali ungerudisha | `5 !== 6 // true` |
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✅ Angalia uelewa wako kwa kuandika kulinganisha kadhaa kwenye koni ya kivinjari chako. Je, data yoyote iliyorejeshwa inakushangaza?
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## Tamko la If
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Tamko la `if` litaendesha msimbo uliopo kati ya vizuizi vyake ikiwa sharti ni `true`.
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```javascript
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if (condition) {
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//Condition is true. Code in this block will run.
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}
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```
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Waendeshaji wa mantiki mara nyingi hutumika kuunda sharti.
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```javascript
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let currentMoney;
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let laptopPrice;
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if (currentMoney >= laptopPrice) {
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//Condition is true. Code in this block will run.
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console.log("Getting a new laptop!");
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}
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```
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## Tamko la If..Else
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Tamko la `else` litaendesha msimbo uliopo kati ya vizuizi vyake wakati sharti ni `false`. Ni hiari na tamko la `if`.
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```javascript
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let currentMoney;
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let laptopPrice;
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if (currentMoney >= laptopPrice) {
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//Condition is true. Code in this block will run.
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console.log("Getting a new laptop!");
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} else {
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//Condition is false. Code in this block will run.
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console.log("Can't afford a new laptop, yet!");
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}
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```
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✅ Jaribu uelewa wako wa msimbo huu na msimbo ufuatao kwa kuendesha kwenye koni ya kivinjari. Badilisha thamani za vigezo vya `currentMoney` na `laptopPrice` ili kubadilisha kile kinachorejeshwa na `console.log()`.
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## Tamko la Switch
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Tamko la `switch` linatumika kufanya vitendo tofauti kulingana na masharti tofauti. Tumia tamko la `switch` kuchagua moja ya vizuizi vingi vya msimbo kuendeshwa.
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```javascript
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switch (expression) {
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case x:
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// code block
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break;
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case y:
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// code block
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break;
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default:
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// code block
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}
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```
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```javascript
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// program using switch statement
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let a = 2;
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switch (a) {
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case 1:
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a = "one";
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break;
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case 2:
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a = "two";
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break;
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default:
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a = "not found";
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break;
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}
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console.log(`The value is ${a}`);
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```
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✅ Jaribu uelewa wako wa msimbo huu na msimbo ufuatao kwa kuendesha kwenye koni ya kivinjari. Badilisha thamani za kigezo `a` ili kubadilisha kile kinachorejeshwa na `console.log()`.
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## Waendeshaji wa Mantiki na Booleans
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Maamuzi yanaweza kuhitaji kulinganisha zaidi ya moja, na yanaweza kuunganishwa pamoja na waendeshaji wa mantiki ili kuzalisha thamani ya Boolean.
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| Alama | Maelezo | Mfano |
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| ------ | ------------------------------------------------------------------------------------------- | --------------------------------------------------------------------- |
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| `&&` | **Mantiki AND**: Inalinganisha maelezo mawili ya Boolean. Inarudisha `true` **tu** ikiwa pande zote mbili ni `true` | `(5 > 6) && (5 < 6 ) //Upande mmoja ni false, mwingine ni true. Inarudisha false` |
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| `\|\|` | **Mantiki OR**: Inalinganisha maelezo mawili ya Boolean. Inarudisha `true` ikiwa angalau upande mmoja ni `true` | `(5 > 6) \|\| (5 < 6) //Upande mmoja ni false, mwingine ni true. Inarudisha true` |
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| `!` | **Mantiki NOT**: Inarudisha thamani kinyume ya maelezo ya Boolean | `!(5 > 6) // 5 si kubwa kuliko 6, lakini "!" itarudisha true` |
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## Masharti na Maamuzi kwa Waendeshaji wa Mantiki
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Waendeshaji wa mantiki wanaweza kutumika kuunda masharti katika tamko la `if..else`.
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```javascript
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let currentMoney;
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let laptopPrice;
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let laptopDiscountPrice = laptopPrice - laptopPrice * 0.2; //Laptop price at 20 percent off
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if (currentMoney >= laptopPrice || currentMoney >= laptopDiscountPrice) {
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//Condition is true. Code in this block will run.
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console.log("Getting a new laptop!");
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} else {
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//Condition is true. Code in this block will run.
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console.log("Can't afford a new laptop, yet!");
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}
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```
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### Waendeshaji wa Negation
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Umeona hadi sasa jinsi unavyoweza kutumia tamko la `if...else` kuunda mantiki ya masharti. Kila kitu kinachoingia kwenye `if` kinahitaji kutathminiwa kuwa `true` au `false`. Kwa kutumia waendeshaji wa `!` unaweza _kukanusha_ maelezo. Inaweza kuonekana kama hivi:
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```javascript
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if (!condition) {
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// runs if condition is false
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} else {
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// runs if condition is true
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}
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```
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### Maelezo ya Ternary
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`if...else` si njia pekee ya kueleza mantiki ya maamuzi. Unaweza pia kutumia kitu kinachoitwa waendeshaji wa ternary. Sintaksia yake inaonekana kama hivi:
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```javascript
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let variable = condition ? <return this if true> : <return this if false>
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```
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Hapa chini kuna mfano wa kueleweka zaidi:
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```javascript
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let firstNumber = 20;
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let secondNumber = 10;
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let biggestNumber = firstNumber > secondNumber ? firstNumber : secondNumber;
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```
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✅ Chukua dakika kusoma msimbo huu mara kadhaa. Je, unaelewa jinsi waendeshaji hawa wanavyofanya kazi?
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Hapo juu inasema kwamba:
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- ikiwa `firstNumber` ni kubwa kuliko `secondNumber`
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- basi weka `firstNumber` kwa `biggestNumber`
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- vinginevyo weka `secondNumber`.
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Maelezo ya ternary ni njia fupi ya kuandika msimbo hapa chini:
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```javascript
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let biggestNumber;
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if (firstNumber > secondNumber) {
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biggestNumber = firstNumber;
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} else {
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biggestNumber = secondNumber;
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}
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```
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---
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## 🚀 Changamoto
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Unda programu ambayo imeandikwa kwanza kwa waendeshaji wa mantiki, kisha iandike upya kwa kutumia maelezo ya ternary. Je, ni sintaksia ipi unayopendelea?
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---
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## Maswali ya Baada ya Somo
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[Maswali ya baada ya somo](https://ff-quizzes.netlify.app/web/quiz/12)
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## Mapitio na Kujisomea
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Soma zaidi kuhusu waendeshaji wengi waliopo kwa mtumiaji [kwenye MDN](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Operators).
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Pitisha kupitia zana nzuri ya Josh Comeau ya [operator lookup](https://joshwcomeau.com/operator-lookup/)!
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## Kazi
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[Waendeshaji](assignment.md)
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---
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**Kanusho**:
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Hati hii imetafsiriwa kwa kutumia huduma ya tafsiri ya AI [Co-op Translator](https://github.com/Azure/co-op-translator). Ingawa tunajitahidi kwa usahihi, tafadhali fahamu kuwa tafsiri za kiotomatiki zinaweza kuwa na makosa au kutokuwa sahihi. Hati ya asili katika lugha yake ya awali inapaswa kuzingatiwa kama chanzo cha mamlaka. Kwa taarifa muhimu, inashauriwa kutumia huduma ya tafsiri ya kitaalamu ya binadamu. Hatutawajibika kwa kutoelewana au tafsiri zisizo sahihi zinazotokana na matumizi ya tafsiri hii. |
