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JavaScript - loops: for, while, do while
7 points
In this article, we would like to show you a few kinds of loops available in JavaScript.
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for (var i = 0; i < 5; ++i) {2
console.log(i);3
}xxxxxxxxxx1
let array = [1, 2, 3, 'text'];2
3
for (let entry of array) {4
console.log(entry);5
}Note: this loop has been added in ECMAScript 2015 (6th Edition).
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var object = {2
'key1' : {3
name : 'John',4
age : 435
},6
'key2' : {7
name : 'Kate',8
age : 549
},10
'key3' : {11
name : 'Diego',12
age : 2113
},14
};15
16
for (var key in object) {17
if (object.hasOwnProperty(key)) {18
var entry = object[key];19
20
console.log(key + ' : ' + entry.name + ', ' + entry.age);21
}22
}Note:
for...inloop only iterates over enumerable and non-Symbol properties.
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var value = 0;2
3
while (value < 10) {4
value += 2;5
console.log(value);6
}xxxxxxxxxx1
var value = 0;2
3
do {4
value += 2;5
console.log(value);6
} while (value < 10);xxxxxxxxxx1
for (var i = 0; ; ++i) {2
if(i >= 5) {3
break;4
}5
6
console.log(i);7
}xxxxxxxxxx1
let array = [1, 2, 3, 'text'];2
3
for (let entry of array) {4
if(entry == 3) {5
break;6
}7
8
console.log(entry);9
}Note: this loop has been added in ECMAScript 2015 (6th Edition).
xxxxxxxxxx1
var object = {2
'key1' : {3
name : 'John',4
age : 435
},6
'key2' : {7
name : 'Kate',8
age : 549
},10
'key3' : {11
name : 'Diego',12
age : 2113
},14
};15
16
for (var key in object) {17
if (key == 'key3') {18
break;19
}20
21
var entry = object[key];22
23
console.log(key + ' : ' + entry.name + ', ' + entry.age);24
}