Comprehensive Guide to JavaScript Control Structures and Object Handling

IF STATEMENT IF (CONDITION) { STATEMENTS 1; } [ELSE { STATEMENTS 2; } ]

SWITCH STATEMENT SWITCH(EXPRESSION) { CASE LABEL : STATEMENTS; BREAK; CASE LABEL : STATEMENTS; BREAK; . . . DEFAULT : STATEMENTS; }

FOR LOOP FOR ([INITIAL EXPRESSION]; [CONDITION]; [INCREMENTEXPRESSION];) { STATEMENTS; }

WHILE LOOP WHILE (CONDITION) { STATEMENTS; }

LABEL STATEMENTS LABEL: STATEMENTS CONTINUE CONTINUE [LABEL] BREAK BREAK [LABEL]

FOR IN STATEMENT FOR ( VARIABLE IN OBJECT) { STATEMENTS }

With statement With statement is used to avoid repeatedly specifying the object prefix syntax : with (object) { statements }

ARGUMENTS ARRAY FUNCTIONNAME.ARGUMENTS[INDEX] EXAMPLE: ADDITION.ARGUMENTS[0]

PREDEFINED FUNCTIONS • evel evaluates a string • isFinite evaluates a number whether finite or not • isNaN tests an argument is NOT A NUMBER • parseInt and parseFloat Returns int or float from string • Number and String Converts an object to Number/ String • escape Returns hexadecimal charecters in ISO • unescape Returns ASCII string for hexadecimal encoding

Working with objects • CREATING NEW OBJECTS • OBJECTS AND PROPERTIES • PREDEFINED CORE OBJECTS LIKE ARRAY , MATH, DATE etc.

CREATING NEW OBJECTS Objects can be created using Object Initializers The syntax is objectname = {property1:value1, property2:value2, … propertyn:valuen} Ex - > student = {sno:102, sna:”rama”, total:234}

Objects using constructor Here 1 ) define the object with constructor 2) create object with new operator ex -> function employe(eno,ena,bsal) { this.eno = eno this.ena = ena this.bsal = bsal } var emp = new employe(200,”ramana”,3500) emp.eno = 100 emp.ena = “krishna” emp.bsal = 5000

Defining properties for an object std.fee = 6500 Defining methods Object.methodname = functionname Deleting properties and objects delete std delete emp.bsal

ARRAY OBJECT METHODS • CONCAT JOINS TWO ARRAYS & RETURNS NEW ARRAY • JOIN JOINS ALL ELEMENTS OF AN ARRAY INTO A STRING • POP REMOVES THE LAST ELEMENT OF AN ARRAY AND RETURNS THAT ELEMENT • PUSH ADDS ONE OR MORE ELEMENTS TO THE END OF AN ARRAY AND RETURNS THE LAST ELEMENT NO. ADDED

ARRAY OBJECT METHODS • REVERSE TRANSPOSE THE ELEMENTS OF AN ARRAY • SHIFT REMOVES THE FIRST ELEMENT FROM AN ARRAY AND RETURNS THAT ELEMENT • SLICE EXTRACTS A SECTION OF AN ARRAY AND RETURNS A NEW ARRAY • SORT SORTS THE ARRAY • UNSHIFT ADDS ONE OR MORE ELEMENTS TO THE FRONT OF ARRAY

DATE OBJECT METHODS getDate () returns date within month (1-31) getDay returns day within week (0-6) getHours() returns hour (0-23) getMinutes() returns minutes (0-59) getMonth() returns month (1-12) getSeconds() returns seconds (0-59) getTime() return number of milli seconds since 1/1/70 00:00:00 getYear() returns year getTimeZoneOffsetr() returns minutes offset • From gmt

Date Object methods • setDate(value) sets date within month (1-31) • setHours(value) • setMinutes(value) • setSeconds(value) • setMonth(value) sets month within year(1-12) • setTime(value) sets number of milli seconds • setYear(value) sets number of years since 1900

Date object parameters • Nothing creates an object with current date • “month dd,yyyy hh:mm:ss” creates an object with the specified date and time • yy,mm,dd creates an object with the specified date values • yy,mm,dd,hh,mm,ss creates an object with the specified date and time

Math object methods • Abs(value) • acos(value) • asin(value) • atan(value) • ceil(value) • cos(value) • floor(value) • exp(value) • log(value) • max(value1,value2)

Math object methods • Min(value1,value2) • pow(value1,value2) • random() • round(value) • sin(value) • sqrt(value) • tan(value)

Comprehensive Guide to JavaScript Control Structures and Object Handling