INT222 - Internet Fundamentals Shi, Yue (Sunny) Office: T2095 SENECA COLLEGE

22 Outline JavaScript Build-in Objects JavaScript Built-in/ Global objects:  String  Array  Date  Math  Number  Boolean  Regular Expression Next Class:  HTML

JavaScript Objects Built-in Objects/ Global Objects  String  Array  Date  Math  Number  Boolean  Regular Expression User-defined Objects 3

4 String Object – property & methods String.length - returns the number of character in a string. String.charAt( index) - returns the character at the specific index. - index starts from 0. - var s = “hello”; alert(s[0]); String.charCodeAt(index) - returns the unicode of the character in place of character. - Unicode provides a unique number for every character, no matter what the platform is.

5 String Object - methods String.indexOf( substring)  returns the position at which the character or string begins  -1 means the character or string is not in the string. String.lastIndexOf( substring )  returns the position at which the last occurrence of your character or string.  -1 means the character or string is not in the string.

6 String Object - methods String.substr(startIndex,subLength)  returns a sub string, starting from startIndex with the length subLength e.g., var s= "abcdefg"; alert(s.substr(2,3)); // cde String.substring(startIndex,y)  returns a sub string, starting from index startIndex (inclusive) ending at index y (not inclusive) e.g., var s= "abcdefg"; alert(s.substring(2,3)); //c

7 String Object - methods String.toLowerCase( )  converts a string to lowercase. String.toUpperCase( )  converts a string to uppercase.

String Object - methods String.replace(srchStr, repStr) – searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced. E.g., var s="Hello all!"; var x=s.replace("all","ALL"); alert(x); Outpu: Hello ALL!

String.trim() – Trim white space from the beginning and the end String.trimLeft() – Trim white space from the left side String.trimRight() – Trim white space from the right side var s = " Good morning "; var n1 = s.length; var n2 = s.trim().length; alert(n1 + "-----"+ n2); 9 String Object - methods

var s= "Hello ALL!"; var len= s.length; alert("Length of " + s + " is " + len); alert("string is: "+s + "\n" + "charAt(2) is: "+ s.charAt(2) + "\n"+ "charCodeAt(6) is: " + s.charCodeAt(6) + "\n"+ "indexOf('l') is: " + s.indexOf('l')+ "\n" + "indexOf('all') is: " + s.indexOf('all')+ "\n" + "lastIndexOf('l') is: " + s.lastIndexOf('l')+ "\n" + "lastIndexOf('all') is: " + s.lastIndexOf('all')+ "\n" + "substr(2,4) is " + s.substr(2,4) + "\n" + "substr(2, 20) is " + s.substr(2,20)+ "\n" + "substring(2,4) is "+ s.substring(2,4) + "\n" + "substring(2,20) is " + s.substring(2, 20) + "\n" + "toLowerCase() is " + s.toLowerCase() + "\n" + "toUpperCase() is " + s.toUpperCase() + " \n" + "replace('ALL ! ', ' all ') is " + s.replace("ALL !", " all ") + "\n "+ "trim() is " + s.trim() );

Summary of String property/ functions var s = “Hello”; s.length s.charAt( index) s.charCodeAt(index) s.indexOf( substring) s.lastIndexOf(substring) s.substr(startIndex,subLength) s.substring(startIndex,y) s.toLowerCase( ) s.toUpperCase( ) s.replace(srchStr, repStr) s.trim() s.trimLeft() s.trimRight() 11

12 Array Object Index starts from 0. When dealing with arrays,  defining an array  assigning values (initializing) to an array  accessing an array  updating an array

13 Array Object Defining an array (1) var name_of_array = new Array(number_of_elements); var product = new Array(5); (2) var product= new Array("books","..","..","..","plates"); (3) var product = [“books”, "..","..","..","plates“]; (4) var product = []; Assigning values (initializing) to an array var product= new Array(5) product[0]="books"; product[1]="cars"; product[2]="cups"; product[3]="dishes"; product[4]="plates";

14 Array Object Accessing an array for (var x=0; x<product.length; x++) { alert(“No. " + x + " is " + product[x]); } Updating an array assign a new value to that occurrenece: product[3]=“cutlery”;

15 Array Object - Property Array.length property  return the number of occurrences in an array (how many items in an array).  alert(“the length of the array is " + product.length);

Array Object - methods Array.concat(arr1,arr2, …, arrN): Joins two or more arrays, and returns a copy of the joined arrays. var array1 = ["a1", "a2"]; var array2 = new Array(); array2[0] = "b0"; array2[1]="b1"; array2[2] = "b2"; var array3=["c1", "c2", "c3"] var con1 = array1.concat(array2, array3); alert(con1); alert(con1[3]); // b1 alert(con1.join()); alert(con1.join(" and "));

17 Array Object - methods Array.join( separator)  Return a string, which joins all the elements of an array, separated by a specified string separator (if none is specified, the default is a comma). product.join(); product.join("*"); product.join(“ and "); product.join(" "); Array.toString(): Converts an array to a string, and returns the result. – var array1 = ["a1", "a2"]; alert(array1.toString()+"..."); // a1, a2…

Array.indexOf(elem): Search the array for an element and returns it's FIRST position, if not found, return -1. – var array1 = ["a1", "a2", "a1"]; alert(array1.indexOf("a1")); //0 Array.lastIndexOf(elem): Search the array for an element, starting at the end, and returns it's position. – var array1 = ["a1", "a2", "a1"]; alert(array1.lastIndexOf("a1")); // 2 Array Object - methods

Array.reverse(): Reverses the order of the elements in an array. – alert(array1.reverse().join()); Array.sort(): Sorts the elements of an array. – var array1 = ["ba1", "ca2", "a3"]; array1.sort(); alert(array1); Descending order ? Array Object - methods Sort & reverse

Array.pop(): Removes the last element of an array, and returns that element – var array1 = ["a1", "a2", "a3"]; var x = array1.pop(); alert(x); // a3 Array.push(new_Element): Adds new elements to the end of an array, and returns the new length. – var array1 = ["a1", "a2", "a3"]; var x = array1.push("a4"); alert(array1); alert(x); // 4 Array Object - methods

Array.shift(): Removes the first element of an array, and returns that element. – var array1 = ["ba1", "ca2", "a3"]; var x = array1.shift(); alert(x); // ba1 Array.unshift():Adds new elements to the beginning of an array, and returns the new length. – var array1 = ["ba1", "ca2", "a3"]; var x = array1.unshift("a5", "a6"); alert(x); // 5 alert(array1); // a5, a6, ba1, ca2, a3 Array Object - methods

Array.slice(start, end): returns the selected elements in an array, as a new array object. selects the elements starting at the given start argument, and ends at, but does not include, the given end argument. Note: The original array will not be changed. – var array1 = ["ba1", "ca2", "a3"]; var x = array1.unshift("a5", "a6"); alert(array1); // a5, a6, ba1, ca2, a3 alert(array1.slice(1,3)); // a6, ba1 Array Object - methods

Summer of Array property/ functions Array.length Array.concat(arr1,arr2, …, arrN) Array.join( separator) Array.indexOf(elem): Array.lastIndexOf(elem): Array.reverse(): Array.sort(): Array.pop(): Array.push(new_Element): Array.shift(): Array.unshift(): Array.slice(start, end):

24 Date Object Getter  getMonth() returns 0 through = January  getDate() returns 1 through 31  getDay() returns 0 through = Sunday  getFullYear() returns 4 digit year  getHours() returns 0 through 23  getMinutes() returns 0 through 59  getSeconds() returns 0 through 59  getMilliseconds() returns 0 through 999  toLocaleString() returns the local date/time as a string.  toGMTString() returns the GMt date/time as a string. GMT: Greenwich Mean Time 

var d = new Date(); alert(d); alert("getMonth() = "+ d.getMonth()); alert("getDate() = "+ d.getDate()); alert("getDay() = "+ d.getDay()); alert("getFullYear() = "+ d.getFullYear()); alert("getHours() = "+ d.getHours()); alert("getTime()" + d.getTime()); alert("toLocaleString() = "+ d.toLocaleString()); alert("toGMTString()" + d.toGMTString()); Example:

26 Date Object Four ways of instantiating a date:  new Date() // current date and time  new Date(milliseconds) //milliseconds since 1970/01/01  new Date(dateString)  new Date(year, month, day, hours, minutes, seconds, milliseconds) today = new Date() var d1 = new Date("October 13, :13:00") var d2 = new Date(79,5,24) var d3 = new Date(79,5,24,11,33,0) var d4 = new Date("2015/1/13 09:32");

27 Date Object setter  setMonth() set month 0 through = January  setDate() set date of month 1 through 31  setDay() set day of week 0 through = Sunday  setFullYear() set 4 digit year  setHours() set hours 0 through 23  setMinutes() set minutes 0 through 59  setSeconds() set seconds 0 through 59  setMilliseconds() set milliseconds 0 through 999

28 Date Object Example: new_date=new Date(); alert(new_date); new_date.setMonth(3); // 0 through 11 alert(new_date); new_date.setDate(10); // 1 through 31 alert(new_date); new_date.setFullYear(1989); // 4 digit year alert(new_date);

29 Date Object Compare two dates: Calculate the difference in Milliseconds var x=new Date(); x.setFullYear(2015,11,25); var today = new Date(); if (today<x) { alert("Today is before this year’s Christmas"); var y = x-today; alert("There are "+ y + "Milliseconds"); var k = y/1000/60/60/24; alert("There are "+ k + "days"); } else { alert("Today is after Christmas"); }

30 Math Object - Properties PropertyDescription EReturns Euler's number (approx ) LN2Returns the natural logarithm of 2 (approx ) LN10Returns the natural logarithm of 10 (approx ) LOG2EReturns the base-2 logarithm of E (approx ) LOG10EReturns the base-10 logarithm of E (approx ) PIReturns PI (approx ) SQRT1_2Returns the square root of 1/2 (approx ) SQRT2Returns the square root of 2 (approx ) alert("Euler's number: " + Math.E);

31 MethodDescription abs(x)Returns the absolute value of x acos(x)Returns the arccosine of x, in radians asin(x)Returns the arcsine of x, in radians atan(x) Returns the arctangent of x as a numeric value between -PI/2 and PI/2 radians atan2(y,x)Returns the arctangent of the quotient of its arguments ceil(x)Returns x, rounded upwards to the nearest integer cos(x)Returns the cosine of x (x is in radians) exp(x)Returns the value of E x floor(x)Returns x, rounded downwards to the nearest integer log(x)Returns the natural logarithm (base E) of x max(x,y,z,...,n)Returns the number with the highest value min(x,y,z,...,n)Returns the number with the lowest value pow(x,y)Returns the value of x to the power of y random()Returns a random number between 0 and 1 round(x)Rounds x to the nearest integer sin(x)Returns the sine of x (x is in radians) sqrt(x)Returns the square root of x tan(x)Returns the tangent of an angle Math Object Methods alert("abs: " + Math.abs(-6));

Number Object PropertyDescription MAX_VALUE Returns the largest number possible in JavaScript( e+308 ) MIN_VALUE Returns the smallest number possible in JavaScript (5e-324 ) NEGATIVE_ INFINITY Returns negative infinity (-Infinity) POSITIVE_I NFINITY Represents infinity (returned on overflow) NaNRepresent a “Not-a-Number” value (isNaN()) The Number object is an object wrapper for primitive numeric values. Number objects are created with new Number(). var num = new Number(value); If the value parameter cannot be converted into a number, it returns NaN (Not-a-Number). These properties can only be accessed as Number.MAX_VALUE.

Number Object - methods toFixed(x): – formats a number to a specified number (x) of digits after decimal point. – X is optional. Default is 0 (no digits after the decimal point). var num = new Number( ); var a = num.toFixed(); // 13 var b = num.toFixed(2); // var c = num.toFixed(3); // var d = num.toFixed(6); // alert("= " + a + '\n' + b+ '\n'+c+ '\n'+d);

Number Object - methods toPrecision(x): – formats a number to a specified length (x). – A decimal point and nulls are added (if needed), to create the specified length. var num = new Number( ); var a = num.toPrecision(); // var b = num.toPrecision(2); // 13 var c = num.toPrecision(3); // 13.4 var d = num.toPrecision(10); // alert("= " + a + '\n' + b+ '\n'+c+ '\n'+d);

Number Object - Methods valueOf() :return the primitive value of a Number object. var num = 15; var n = num.valueOf();

Number Object - methods toString(radix): converts a Number object to a string. var num = 15; var a = num.toString() //15 var b = num.toString(2); // 1111 var c = num.toString(8); // 17 var d = num.toString(16); //f

Boolean Object two values: true or false. Create a Boolean object: – var myBoolean=new Boolean(value); – Value is optional. If no initial value, or one of the following: – 0 – -0 – null – "" – false – undefined – NaN The Boolean object is set to false.

Boolean Object - Methods toString(): – Converts a Boolean value to a string, and returns the result. var bool = new Boolean(1); var myvar = bool.toString(); alert(myvar); output: true

Boolean Object - Methods valueOf(): – Returns the primitive value of a Boolean object var bool = new Boolean(null); var myvar = bool.valueOf(); alert(myvar); output: false

Regular expressions: patterns used to match character combinations in strings. Regular expressions are objects. To search in a text, use a pattern to describe what you are searching for. Are used to perform powerful pattern-matching and "search-and-replace" functions on text. 40 Regular Expression

Syntax: var patt=new RegExp(pattern,modifiers); var patt=/pattern/modifiers; – Pattern: specifies the pattern of an expression – Modifiers: specify if a search should be global (g), case- insensitive (i), etc. E.g., – var patt1=new RegExp(“is”, g); – var patt1=/is/g;

42 Regular Expression - Methods RegularExpression.test(string): -Searches a string for a specified value, and returns true or false, depending on the result. var str="Is this all there is?"; var patt=new RegExp("E", "i"); alert("pattern ‘E' is in 'str': " + patt.test(str)); output - pattern ‘E' is in 'str': true var str="Is this all there is?"; var patt=new RegExp("E"); alert("pattern ‘E' is in 'str': " + patt.test(str)); output - pattern ‘E' is in 'str': false

43 Regular Expression - Methods RegularExpression.exec(string): searches a string for a specified value, – returns a result array or null. var str="Is this all there is?"; var patt=new RegExp("is", "i"); alert("pattern ‘is' is in 'str': " + patt.exec(str)); output - pattern ‘is' is in 'str': Is

44 Regular Expression - Methods String.match(pattern): - returns the matching patterns, - if no matching, return null. - without the modifier “g”, returns same as exec(); var str="Is this all there is?"; var patt=/is/g; alert(str.match(patt));  output - is,is var str="Is this all there is?"; var patt1=/is/gi; alert(str.match(patt1));  output – Is, is,is

Regular Expression - Methods String.search(RegularExpression): – search the RegularExpression in the specified string. – Return the index of the first match of the RegularExpression in the string, – Return -1, if no match – E.g., var re = /or/; var s = "Good morning"; alert(s.search(re)); // 6 45

Regular Expression – Special Characters *: matches the preceding character 0 or more times,  /ab*c/ matches “abbbbc” and “ac”, but not “ad” +: matches the preceding character 1 or more times  /ab+c/ matches “abbbc” and “abc”, but not “ac” ?: matches the preceding character 0 or 1 time.  /ab?c/ matches “abc” and “ac” ^: Matches beginning of input $: Matches end of input {n}: Matches exactly n occurrences of the preceding character. N must be a positive integer. More on MDN (Mozilla Developer Network): US/docs/Web/JavaScript/Guide/Regular_Expressions US/docs/Web/JavaScript/Guide/Regular_Expressions 46

Regular Expression - Brackets Brackets are used to find a range of characters

Example var name = prompt("Enter a name"); var nameRegEx = /^[A-Za-z][0-9 A-Za-z \'\-]*$/; if(nameRegEx.test(name)==true) alert("Yes"); else alert("No"); 48

Example var phone = prompt("Enter Phone:"); var phoneRegExp = /^\([0-9]{3}\)[0-9]{3}\-[0-9]{4}$/; if(phoneRegExp.test(phone)==true) {alert("Yes");} else alert("No"); 49

Next Class HTML 50

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