I am so new on typescript/javascript that I would like to modify each element of array with some function like following code. but I am wondering if there is a more concise/clear way to build my expected array from variable?
const variable = [1,2,3,4,5,6]
function add(a: number, b: number): number {
return a + b;
}
console.log(variable.map((i: number) => {return add(100, i)})) # =>[ 101, 102, 103, 104, 105, 106 ]
One semi-generic approach would be to define a function add(), which itself returns a function where the current item being mapped is added to the fixed amount specified (ie 100):
const add = (amount) => (item) => item + amount;
console.log([1,2,3,4,5,6].map(add(100)));In ES6, if you have single expression as a return statement then you can simply re-write it as:
variable.map((i: number) => add(100, i))
Also, if you declare variable as an array of number like:
const variable: number[] = [1,2,3,4,5,6]
Then inside .map() method you will not need to declare i: number as that would be automatically inferred. So, the .map() logic will become even more concise like:
variable.map(i => add(100, i))
Or, you can simply do it without using the add() function here:
variable.map(i => 100 + i)
You don't really need to create an add function, you can directly add the number to current value during mapping.
const variable = [1,2,3,4,5,6]
console.log(variable.map(num => num + 100))
returnstatement in map's callback and remove curly brackets if only single expression is needed.