EN
TypeScript - create and use functions
0 points
In TypeScript it is possible to create and use functions in few ways.
xxxxxxxxxx1
const action1 = Function('console.log("This is my message...");');2
const action2 = Function('console.log(arguments);');3
const action3 = new Function('console.log("This is my message...");');4
const action4 = new Function('console.log(arguments);');5
6
action1();7
action2(1, 2, 3, 'test 1', 'text 2', 'text n');8
action3();9
action4(1, 2, 3, 'test 1', 'text 2', 'text n');10
11
console.log(action1.name);12
console.log(action2.name);13
console.log(action3.name);14
console.log(action4.name);Output (with NodeJS):
xxxxxxxxxx1
This is my message...2
3
[Arguments] {4
'0': 1,5
'1': 2,6
'2': 3,7
'3': 'test 1',8
'4': 'text 2',9
'5': 'text n'10
}11
12
This is my message...13
14
[Arguments] {15
'0': 1,16
'1': 2,17
'2': 3,18
'3': 'test 1',19
'4': 'text 2',20
'5': 'text n'21
}22
23
anonymous24
anonymous25
anonymous26
anonymousxxxxxxxxxx1
const action = function(): void {2
console.log('This is my message...');3
};4
5
const sum1 = function(a: number, b: number): number {6
return a + b;7
};8
9
const sum2 = function(args: number[]): number {10
let result = 0;11
for (let i = 0; i < args.length; ++i) {12
result += args[i];13
}14
return result;15
};16
17
const display = function(a: number, b: number, args: number[]): void {18
let text = '';19
text += 'a=' + a + ', ';20
text += 'b=' + b + ', ';21
text += 'args=[';22
for (let i = 0; i < args.length; ++i) {23
if (i > 0) {24
text += ', ';25
}26
text += args[i];27
}28
text += ']';29
console.log(text);30
};31
32
action();33
console.log(sum1(1, 2));34
console.log(sum2(1, 2, 3, 4, 5));35
display(1, 2, 3, 4, 5);36
37
console.log(action.name);38
console.log(sum1.name);39
console.log(sum2.name);40
console.log(display.name);Output (with NodeJS):
xxxxxxxxxx1
This is my message...2
33
154
a=1, b=2, args=[3, 4, 5]5
action6
sum17
sum28
displayxxxxxxxxxx1
const action = function MyFunctionName(): void {2
console.log('This is my message...');3
};4
5
const sum1 = function MyFunctionName(a: number, b: number): number {6
return a + b;7
};8
9
const sum2 = function MyFunctionName(10
a: number,11
b: number,12
args: number[]13
): number {14
let result = 0;15
16
for (let i = 0; i < args.length; ++i) {17
result += args[i];18
}19
20
return result;21
};22
23
const display = function MyFunctionName(24
a: number,25
b: number,26
args: number[]27
): void {28
let text = '';29
30
text += 'a=' + a + ', ';31
text += 'b=' + b + ', ';32
text += 'args=[';33
34
for (let i = 0; i < args.length; ++i) {35
if (i > 0) {36
text += ', ';37
}38
text += args[i];39
}40
41
text += ']';42
43
console.log(text);44
};45
46
action();47
console.log(sum1(1, 2));48
console.log(sum2(1, 2, 3, 4, 5));49
display(1, 2, 3, 4, 5);50
51
console.log(action.name);52
console.log(sum1.name);53
console.log(sum2.name);54
console.log(display.name);Output (with NodeJS):
xxxxxxxxxx1
This is my message...2
33
124
a=1, b=2, args=[3, 4, 5]5
MyFunctionName6
MyFunctionName7
MyFunctionName8
MyFunctionNameArrow function has been introduced in ES6. This part shows in simple way how to use arrow functions.
3.1. With function body in brackets
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const action1 = (): void => {2
console.log('This is my message...');3
};4
5
const action2 = (args: number[] | string[]): void => {6
console.log(args);7
};8
9
const sum = (a: number, b: number): number => {10
return a + b;11
};12
13
const display = (14
a: number | string,15
b: number | string,16
args: number[] | string[]17
): void => {18
let text = '';19
20
text += 'a=' + a + ', ';21
text += 'b=' + b + ', ';22
text += 'args=[';23
24
for (let i = 0; i < args.length; ++i) {25
if (i > 0) {26
text += ', ';27
}28
text += args[i];29
}30
31
text += ']';32
33
console.log(text);34
};35
36
action1();37
action2(1, 2, 3, 4, 5);38
console.log(sum(1, 2));39
display(1, 2, 3, 4, 5);40
41
console.log(action1.name);42
console.log(action2.name);43
console.log(sum.name);44
console.log(display.name);45
Output (with NodeJS):
xxxxxxxxxx1
This is my message...2
[ 1, 2, 3, 4, 5 ]3
34
a=1, b=2, args=[3, 4, 5]5
6
action17
action28
sum9
display3.2. Without brackets - with auto-returning of values
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const action = (): void => console.log('This is my message...');2
3
const print1 = (text: string): void => console.log(text);4
const print2 = (myArguments: string[] | number[]) =>5
console.log(myArguments);6
const print3 = (7
a: string | number,8
b: string | number,9
myArguments: string[] | number[]10
): void => console.log(a, b, myArguments);11
12
const sum = (a: number, b: number): number => a + b;13
14
action();15
print1('This is my custom text...');16
print2(1, 2, 3, 4, 5);17
print3(1, 2, 3, 4, 5);18
console.log(sum(1, 2));19
20
console.log(action.name);21
console.log(print1.name);22
console.log(print2.name);23
console.log(print3.name);24
console.log(sum.name);Output (with NodeJS):
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This is my message...2
This is my custom text...3
[ 1, 2, 3, 4, 5 ]4
1 2 [ 3, 4, 5 ]5
36
7
action8
print19
print210
print311
sum