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description Loop
keywords js,operator
title loop
toc_max 4

what is loop

loop is a reapeting process in same block (excute over and over in same block)

loop type

  • while
  • do -- while
  • for
  • forEach
  • for ... in
  • for ... of

while

while(yourCondition) {
  statement
  increment/decrement
}
let num = 1;
while (num < 10) {
  console.log(num);
  num++;
}

do while

do () {
  Statements,
  inc/dec
} while (yourCondition);
let num = 1;
do {
  console.log(num);
  num++;
} while (num < 10);
// output: 1,2,3,4,5,6,7,8,9
  • do statement return first then other task
let num = 11;
do {
  console.log(num);
  num++;
} while (num < 10);
// output: 11

for

for (initialization; condition; inc/dec) {
  statement;
}
for (let num = 1; num < 10; num++) {
  console.log(num);
}
// output: 1,2,3,4,5,6,7,8,9
let nums = [];
for (let i = 0 ; i < 10 ; i++) {
  nums.push(i);
}
nums.forEach(t => console.log(t));
//  1,2,3,4,5,6,7,8,9

break

  • loop stop (if fullfill condition)
for (let num = 1; num < 10; num++) {
  if(num == 5) {
    break;
  }
  console.log(num);
}
// output: 1,2,3,4

continue

  • skip (not condition fullfill)
for (let num = 1; num < 10; num++) {
  if(num % 2 != 0) {
    continue;
  }
  console.log(num);
}
// output:
// 2,4,6,8,10

for...in

  • for...in return array index
let users = ['kamal','jamal','maruf','sadia','kalam','karim'];
for (user in users) {
  console.log(user);
}
//output
// 0
// 1
// 2
// 3
// 4
// 5

for...of

  • return array value
let users = ['kamal','jamal','maruf','sadia','kalam','karim'];
for (user of users) {
  console.log(user);
}
// output
// kamal
// jamal
// maruf
// sadia
// kalam
// karim

forEach

let users = ['kamal','jamal','maruf','sadia','kalam','karim'];
users.forEach ((name,index) => {
  console.log(index +' user name '+ 'is' + ' ' + name);
})
// output:
// 0 user name is kamal
// 1 user name is jamal
// 2 user name is maruf
// 3 user name is sadia
// 4 user name is kalam
// 5 user name is karim

references