From d4ac4d146e8b6900bf04b332135d6c6b9cd2a241 Mon Sep 17 00:00:00 2001 From: Asabeneh Date: Fri, 5 Jun 2020 22:53:11 +0300 Subject: [PATCH] day 3 reviewed --- 03_Day/03_booleans_operators_date.md | 91 ++++++++++++++-------------- 1 file changed, 47 insertions(+), 44 deletions(-) diff --git a/03_Day/03_booleans_operators_date.md b/03_Day/03_booleans_operators_date.md index fc856ac1..c7236cbb 100644 --- a/03_Day/03_booleans_operators_date.md +++ b/03_Day/03_booleans_operators_date.md @@ -17,7 +17,7 @@ ![Thirty Days Of JavaScript](../images/banners/day_1_3.png) -- [📔 Day 3](#%f0%9f%93%94-day-3) +- [📔 Day 3](#-day-3) - [Booleans](#booleans) - [Truthy values](#truthy-values) - [Falsy values](#falsy-values) @@ -46,7 +46,7 @@ - [Getting minutes](#getting-minutes) - [Getting seconds](#getting-seconds) - [Getting time](#getting-time) - - [💻 Day 3: Exercises](#%f0%9f%92%bb-day-3-exercises) + - [💻 Day 3: Exercises](#-day-3-exercises) - [Exercises: Level 1](#exercises-level-1) - [Exercises: Level 2](#exercises-level-2) - [Exercises: Level 3](#exercises-level-3) @@ -86,11 +86,11 @@ We agreed that boolean values are either true or false. - the boolean false - '', "", ``, empty string -It is good to remember those truthy values and falsy values. In later section, we will use them with conditions to make decision. +It is good to remember those truthy values and falsy values. In later section, we will use them with conditions to make decisions. ## Undefined -If we declare a variable and if we do not assign a value, the value will be undefined. In addition to this, if a function is not returning the value will be undefined. +If we declare a variable and if we do not assign a value, the value will be undefined. In addition to this, if a function is not returning the value, it will be undefined. ```js let firstName @@ -145,23 +145,26 @@ console.log(sum, diff, mult, div, remainder, powerOf) // 7,1,12,1.33,1, 64 ``` ```js -let PI = 3.14 +const PI = 3.14 let radius = 100 // length in meter -const gravity = 9.81 // in m/s2 -let mass = 72 // in Kilogram -const boilingPoint = 100 // temperature in oC, boiling point of water -const bodyTemp = 37 // body temperature in oC - //Let us calculate area of a circle const areaOfCircle = PI * radius * radius console.log(areaOfCircle) // 314 m + +const gravity = 9.81 // in m/s2 +let mass = 72 // in Kilogram + // Let us calculate weight of an object const weight = mass * gravity console.log(weight) // 706.32 N(Newton) -//Concatenating string with numbers using string interpolation +const boilingPoint = 100 // temperature in oC, boiling point of water +const bodyTemp = 37 // body temperature in oC + + +// Concatenating string with numbers using string interpolation /* The boiling point of water is 100 oC. Human body temperature is 37 oC. @@ -190,14 +193,13 @@ console.log(3 != 2) // true, because 3 is not equal to 2 console.log(3 == '3') // true, compare only value console.log(3 === '3') // false, compare both value and data type console.log(3 !== '3') // true, compare both value and data type -console.log(3 !== '3') // true, compare both value and data type console.log(3 != 3) // false, compare only value console.log(3 !== 3) // false, compare both value and data type console.log(0 == false) // true, equivalent +console.log(0 === false) // false, not exactly the same console.log(0 == '') // true, equivalent console.log(0 == ' ') // true, equivalent console.log(0 === '') // false, not exactly the same -console.log(0 === false) // false, not exactly the same console.log(1 == true) // true, equivalent console.log(1 === true) // false, not exactly the same console.log(undefined == null) // true @@ -209,13 +211,13 @@ console.log(typeof NaN) // number console.log('mango'.length == 'avocado'.length) // false console.log('mango'.length != 'avocado'.length) // true console.log('mango'.length < 'avocado'.length) // true -console.log('milk'.length != 'meat'.length) // false console.log('milk'.length == 'meat'.length) // true +console.log('milk'.length != 'meat'.length) // false console.log('tomato'.length == 'potato'.length) // true console.log('python'.length > 'dragon'.length) // false ``` -Try to understand the above comparisons with some logic. Remember without any logic might be difficult. +Try to understand the above comparisons with some logic. Remembering without any logic might be difficult. JavaScript is some how a wired kind of programming language. JavaScript code run and give you a result but unless you are good at it may not be the desired result. As rule of thumb, if a value is not true with == it will not be equal with ===. Using === is safer than using ==. The following [link](https://dorey.github.io/JavaScript-Equality-Table/) has an exhaustive list of comparison of data types. @@ -224,30 +226,30 @@ As rule of thumb, if a value is not true with == it will not be equal with ===. The following symbols are the common logical operators: &&(ampersand) , ||(pipe) and !(negation). -&& gets true only if the two operands are true. -|| gets true either of the operand is true. -! negates true to false, false to true. +The && operator gets true only if the two operands are true. +The || operator gets true either of the operand is true. +The ! operator negates true to false and false to true. ```js -//&& ampersand operator example +// && ampersand operator example -const check = 4 > 3 && 10 > 5 // true && true -> true -const check = 4 > 3 && 10 < 5 // true && false -> false -const check = 4 < 3 && 10 < 5 // false && false -> false +const check = 4 > 3 && 10 > 5 // true && true -> true +const check = 4 > 3 && 10 < 5 // true && false -> false +const check = 4 < 3 && 10 < 5 // false && false -> false -//|| pipe or operator, example +// || pipe or operator, example -const check = 4 > 3 || 10 > 5 // true || true -> true -const check = 4 > 3 || 10 < 5 // true || false -> true -const check = 4 < 3 || 10 < 5 // false || false -> false +const check = 4 > 3 || 10 > 5 // true || true -> true +const check = 4 > 3 || 10 < 5 // true || false -> true +const check = 4 < 3 || 10 < 5 // false || false -> false //! Negation examples -let check = 4 > 3 // true -let check = !(4 > 3) // false +let check = 4 > 3 // true +let check = !(4 > 3) // false let isLightOn = true -let isLightOff = !isLightOn // false -let isMarried = !false // true +let isLightOff = !isLightOn // false +let isMarried = !false // true ``` ### Increment Operator @@ -258,16 +260,16 @@ In JavaScrip we use the increment operator to increase a value stored in a varia ```js let count = 0 -console.log(++count) // 1 -console.log(count) // 1 +console.log(++count) // 1 +console.log(count) // 1 ``` 1. Post-increment ```js let count = 0 -console.log(count++) // 0 -console.log(count) // 1 +console.log(count++) // 0 +console.log(count) // 1 ``` We use most of the time post-increment. At leas you should remember how to use post-increment operator. @@ -349,7 +351,7 @@ alert(message) alert('Welcome to 30DaysOfJavaScript') ``` -Do not use too much alert because it is destructing and annoying, use it just for to test. +Do not use too much alert because it is destructing and annoying, use it just to test. ### Window prompt() method @@ -367,8 +369,8 @@ console.log(number) ### Window confirm() method The confirm() method displays a dialog box with a specified message, along with an OK and a Cancel button. -A confirm box is often used to ask permission from a user to do something. Window confirm() takes an string as an argument. -Clicking the OK yields true value, clicking the Cancel button yields false value. +A confirm box is often used to ask permission from a user to execute something. Window confirm() takes a string as an argument. +Clicking the OK yields true value, whereas clicking the Cancel button yields false value. ```js const agree = confirm('Are you sure you like to delete? ') @@ -397,7 +399,7 @@ We have created a time object and we can access any date time information from t ### Getting full year -Let's extract or get the full from a time object. +Let's extract or get the full year from a time object. ```js const now = new Date() @@ -419,7 +421,7 @@ Let's extract or get the date of the month from a time object. ```js const now = new Date() -console.log(now.getDate()) // 4, because the day of the month is 4th, day(0-31) +console.log(now.getDate()) // 4, because the day of the month is 4th, day(1-31) ``` ### Getting day @@ -428,7 +430,8 @@ Let's extract or get the day of the week from a time object. ```js const now = new Date() -console.log(now.getDay()) // 6, because the day is Saturday which is the 5th day, +console.log(now.getDay()) // 6, because the day is Saturday which is the 7th day +// Sunday is 0, Monday is 1 and Saturday is 6 // Getting the weekday as a number (0-6) ``` @@ -494,7 +497,7 @@ const minutes = now.getMinutes() // return number (0 -59) console.log(`${date}/${month}/${year} ${hours}:${minutes}`) // 4/1/2020 0:56 ``` -🌕 You have boundless energy. You have just completed day 3 challenges and you are three steps a head in to your way to greatness. Now do some exercises for your brain and for your muscle. +🌕 You have boundless energy. You have just completed day 3 challenges and you are three steps a head in to your way to greatness. Now do some exercises for your brain and for your muscle. ## 💻 Day 3: Exercises @@ -618,13 +621,13 @@ console.log(`${date}/${month}/${year} ${hours}:${minutes}`) // 4/1/2020 0:56 ``` 1. Create a human readable time format using the Date time object - 1. YYY-MM-DD HH:mm + 1. YYYY-MM-DD HH:mm 2. DD-MM-YYYY HH:mm - 3. DD/MM/YYY HH:mm + 3. DD/MM/YYYY HH:mm ### Exercises: Level 3 -1. Create a human readable time format using the Date time object. The hour and the minute should be all time two digits(7 hours should be 07 and 5 minutes should be 05 ) +1. Create a human readable time format using the Date time object. The hour and the minute should be all the time two digits(7 hours should be 07 and 5 minutes should be 05 ) 1. YYY-MM-DD HH:mm eg. 20120-01-02 07:05 🎉 CONGRATULATIONS ! 🎉