Control structures are a set of statements that are used to control the flow of execution of a program in JavaScript. These structures allow the program to make decisions and execute different sets of instructions based on certain conditions. In JavaScript, there are three main types of control structures:
1. Conditional Statements :
Conditional statements are used to execute different sets of instructions based on whether a condition is true or false. The most commonly used conditional statements in JavaScript are:
- if statement: It is used to execute a set of statements if a condition is true.
if (condition) {
//Statements to be executed if the
condition is true
}
- if…else statement: It is used to execute a set of statements if a condition is true, and another set of statements if the condition is false.
if (condition) {
//Statements to be executed if the
condition is true
}
else {
//Statements to be executed if the
condition is false
}
- if…else if…else statement: It is used to execute different sets of statements based on different conditions.
if (condition1) {
//Statements to be executed if condition1 is true
}
else if (condition2) {
//Statements to be executed if condition2
is true
}
else {
//Statements to be executed if all
conditions are false
}
- switch statement: It is used to execute different sets of statements based on different values of an expression.
switch(expression){
case value1: //Statements to be executed
if expression matches value1
break ;
case value2: //Statements to be executed
if expression matches value2
break ;
. . .
default : //Statements to be executed if
expression does not match any case
}
2. Looping Statements :
Looping statements are used to execute a set of statements repeatedly until a certain condition is met. The most commonly used looping statements in JavaScript are:
- while loop: It is used to execute a set of statements if a condition is true.
while(condition){
//Statements to be executed as long as
the condition is true
}
- do…while loop :It is used to execute a set of statements at least once and then repeatedly as long as a condition is true.
do {
//Statements to be executed at least once
} while (condition) ;
- for loop :It is used to execute a set of statements a specific number of times.
for( initialization; condition;
increment/decrement){
//Statements to be executed until the
condition is true
}
- for…in loop: It is used to loop through the properties of an object.
for(variable in object){
//Statements to be executed for each
property of the object
}
- for…of loop: It is used to loop through the elements of an iterable object like an array or a string.
for (variable of iterable) {
//Statements to be executed for each
element of the iterable object
}
3. Jump Statements :
Jump statements are used to transfer the control of a program to a different part of the program. The most commonly used jump statements in JavaScript are:
- break statement: It is used to terminate a loop or a switch statement.
for (variable of iterable) {
//Statements to be executed for each
element of the iterable object
}
- continue statement:It is used to skip the current iteration of a loop and continue with the next iteration.
for (i=0 ; i<10 ; i++) {
if (i%2==0) {
continue ;
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