shoaibk-dev · December 24, 2018 06:56
diff --git a/js_practice-1 b/js_practice-1
 // statically typed - type is enforced
 // dynamically typed - infer variables at runtime
 // weakly typed - allow type to be inferred as another type [1 + '2' = '12' => it coerce number into string]
 // type coercion - process of converting value from one type to another
 //  type coercion can be imlicit[operators to value of different types] or explicit[type casting - Number(value)]
 // === strict equality operator => does not trigger implicit type coercion [both type and value we're compairing have to be the same]
 // == loose equality operator on the other hand does both comparision and type coercion [77 == '77' => true - perform type coercion]

 // three type of conversion in js: to string, to boolean, to number
 // conversion login for primitive and object work differently but both can only be converted to those three ways


 // String conversion: all primitives values are converted to string naturally  => String(null) = 'null'

 // Symbol conversion is bit tricky, because it can only be converted explicitly, but not implicitly

 // Boolean Conversion: 
 // Apply the Boolean() function to explicitly convert a value to boolean  => Boolean(2)
 // Implicit conversion happen is locgical context or triggered by logical operators(|| && !)   => if(2) / 2 || 'hello'
 // logical operators do boolean conversion internally but return the value of original operands

 // Numeric conversion: 
 // explicit conversion - Number()
 // implicit conversion is tricky, because it triggered in more cases

 // 2 special rule: 
 // 1 - when applying == to null or undefined numerci conversion does not happen. [null equals only to null or undefined]
 // 2 - NaN does not equal to anything even itself

 // ______________________________________________________________________________________

 // Number and Maths: 
 // numbers are stored as double floating point numbers [All numbers are float]


 // RegEx: is simply a type of object that is used to match character combinations in string.
 // two ways to construct a RegEx;
 // 1- Regular Expression Literal;
 var option = /cat/;  // use literal for constant RegEx
 // 2 - RegEx constructor;
 var option2 = new RegExp("cat"); // if regex will be changing or relying on other variable then use constructor

 console.log("check regEx: " + /cat/.test("hello cat"));


 // Template literal [enclosing back tick] and Tag function[get argument]:
 var name = 'world';
 console.log(`hello ${name}`);

 var p = {
    name: 'jackson',
    nn: 'jak'
 };
 // String concatenation:
 console.log('Hi, I\'m ' + p.name + ' ! call me "' + p.nn +'". ');
 // Template literals:
 console.log(`Hi, I'm ${p.name} ! Call me "${p.nn}".`);

 var name1 = 'Foo';
 var age = 23;
 function greet() {
    console.log(`I'm ${name1}. I'm ${age} year old`);
 }

 console.log(greet `I'm ${name}`);

 // String: Immutable
 let str1 = "abc";
 console.log(str1);
 str1 = "def";
 console.log(str1);


 const str2 = 'some cool sentence, yeah';
 // string to array - use Strimg.split(separator, limit) => return an array of strings and split at each point where separator occurs.
 const word = str2.split(' ');
 console.log(word);

 // remove spaces 
 // - String.trim() => username.trim(); / u2.trimStart() / u3.trimLeft()

 // check if string incluide a specific word
 // m1.includes('swag');
 //  with regex: RegExp(/swag/gi);  re.test(m1);

 // replace part of string; str.replace(RegExp|Str, str|fun);

 // copy part of sentence: String.slice(start, end) =>  return a new string with extracted text
 // with Substring: String.Substring(start, end)

 // capitalize the first letter of a sentence:
 let sentence = "how are you";
 const firstChar = sentence.slice(0, 1).toUpperCase(); // grab the first letter and uppercase it
 const otherChars = sentence.slice(1);
 console.log(sentence = firstChar + otherChars);

 //  get the index of a word; use String.indexOf(search, start) and str.lastIndexOf()

 // pad a word
 let str3 = 'centred title';
 const len = str3.length;
 str3 = str3.padStart(len + len / 2);
 str3.padEnd(len * 2);

 // startsWith, endsWith

 // count how many time phrase occurs

 const input = `I love coffee.
 I buy coffee everyday.
 I'm drinking coffee ... coffee right now.`;

 const wordCount = 'coffee';
 // use string.match(RegExp|str) : g - find all matches : i - to ignore case
 function countWord(str, word) {
    const re = RegExp(word, 'gi');
    const match = (str.match(re) || []);
    const count = match.length;
    return count;
 }

 console.log(countWord(input, wordCount));






 // const a = new Array(3);
 // console.log(a.length);
 // console.log(typeof a);

 // const sum = new Function('a', 'b', 'return a + b');
 // console.log(sum(2, 3));

 // const str = '24.33';
 // const short = +str;
 // const num = Number(str);
 // console.log(num);
 // const bin = '110110'
 // const b = Number.parseInt(bin, 2);
 // console.log(b);

 // console.log(Number.isInteger(5/2));
 // const a1 = 5.27158;
 // console.log(a1.toFixed(2));

 // console.log((23).toString(2));
 // console.log(5 + NaN);

 // // genertate random number between min to max including min and max;
 // const getRandom = (min, max) => {
 //     Math.floor(Math.random() * (max - min + 1)) + min;
 // }

 // console.log(getRandom(1, 7));
	// statically typed - type is enforced
	// dynamically typed - infer variables at runtime
	// weakly typed - allow type to be inferred as another type [1 + '2' = '12' => it coerce number into string]
	// type coercion - process of converting value from one type to another
	// type coercion can be imlicit[operators to value of different types] or explicit[type casting - Number(value)]
	// === strict equality operator => does not trigger implicit type coercion [both type and value we're compairing have to be the same]
	// == loose equality operator on the other hand does both comparision and type coercion [77 == '77' => true - perform type coercion]

	// three type of conversion in js: to string, to boolean, to number
	// conversion login for primitive and object work differently but both can only be converted to those three ways


	// String conversion: all primitives values are converted to string naturally => String(null) = 'null'

	// Symbol conversion is bit tricky, because it can only be converted explicitly, but not implicitly

	// Boolean Conversion:
	// Apply the Boolean() function to explicitly convert a value to boolean => Boolean(2)
	// Implicit conversion happen is locgical context or triggered by logical operators(\|\| && !) => if(2) / 2 \|\| 'hello'
	// logical operators do boolean conversion internally but return the value of original operands

	// Numeric conversion:
	// explicit conversion - Number()
	// implicit conversion is tricky, because it triggered in more cases

	// 2 special rule:
	// 1 - when applying == to null or undefined numerci conversion does not happen. [null equals only to null or undefined]
	// 2 - NaN does not equal to anything even itself

	// ______________________________________________________________________________________

	// Number and Maths:
	// numbers are stored as double floating point numbers [All numbers are float]


	// RegEx: is simply a type of object that is used to match character combinations in string.
	// two ways to construct a RegEx;
	// 1- Regular Expression Literal;
	var option = /cat/; // use literal for constant RegEx
	// 2 - RegEx constructor;
	var option2 = new RegExp("cat"); // if regex will be changing or relying on other variable then use constructor

	console.log("check regEx: " + /cat/.test("hello cat"));


	// Template literal [enclosing back tick] and Tag function[get argument]:
	var name = 'world';
	console.log(`hello ${name}`);

	var p = {
	name: 'jackson',
	nn: 'jak'
	};
	// String concatenation:
	console.log('Hi, I\'m ' + p.name + ' ! call me "' + p.nn +'". ');
	// Template literals:
	console.log(`Hi, I'm ${p.name} ! Call me "${p.nn}".`);

	var name1 = 'Foo';
	var age = 23;
	function greet() {
	console.log(`I'm ${name1}. I'm ${age} year old`);
	}

	console.log(greet `I'm ${name}`);

	// String: Immutable
	let str1 = "abc";
	console.log(str1);
	str1 = "def";
	console.log(str1);


	const str2 = 'some cool sentence, yeah';
	// string to array - use Strimg.split(separator, limit) => return an array of strings and split at each point where separator occurs.
	const word = str2.split(' ');
	console.log(word);

	// remove spaces
	// - String.trim() => username.trim(); / u2.trimStart() / u3.trimLeft()

	// check if string incluide a specific word
	// m1.includes('swag');
	// with regex: RegExp(/swag/gi); re.test(m1);

	// replace part of string; str.replace(RegExp\|Str, str\|fun);

	// copy part of sentence: String.slice(start, end) => return a new string with extracted text
	// with Substring: String.Substring(start, end)

	// capitalize the first letter of a sentence:
	let sentence = "how are you";
	const firstChar = sentence.slice(0, 1).toUpperCase(); // grab the first letter and uppercase it
	const otherChars = sentence.slice(1);
	console.log(sentence = firstChar + otherChars);

	// get the index of a word; use String.indexOf(search, start) and str.lastIndexOf()

	// pad a word
	let str3 = 'centred title';
	const len = str3.length;
	str3 = str3.padStart(len + len / 2);
	str3.padEnd(len * 2);

	// startsWith, endsWith

	// count how many time phrase occurs

	const input = `I love coffee.
	I buy coffee everyday.
	I'm drinking coffee ... coffee right now.`;

	const wordCount = 'coffee';
	// use string.match(RegExp\|str) : g - find all matches : i - to ignore case
	function countWord(str, word) {
	const re = RegExp(word, 'gi');
	const match = (str.match(re) \|\| []);
	const count = match.length;
	return count;
	}

	console.log(countWord(input, wordCount));






	// const a = new Array(3);
	// console.log(a.length);
	// console.log(typeof a);

	// const sum = new Function('a', 'b', 'return a + b');
	// console.log(sum(2, 3));

	// const str = '24.33';
	// const short = +str;
	// const num = Number(str);
	// console.log(num);
	// const bin = '110110'
	// const b = Number.parseInt(bin, 2);
	// console.log(b);

	// console.log(Number.isInteger(5/2));
	// const a1 = 5.27158;
	// console.log(a1.toFixed(2));

	// console.log((23).toString(2));
	// console.log(5 + NaN);

	// // genertate random number between min to max including min and max;
	// const getRandom = (min, max) => {
	// Math.floor(Math.random() * (max - min + 1)) + min;
	// }

	// console.log(getRandom(1, 7));
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