Objective
Write a function values(f, low, high) that yields an array of function values [f(low), f(low + 1), . . ., f(high)].
What I Tried
function values(f, low, high) {
var result = [];
for(var i = low; i < high; i++) {
result.push(j = f(i));
}
return result;
}
const vf = (p1) => console.log(p1);
const arrayOfFuns = values(vf, 10, 16);
console.log(arrayOfFuns);
console.log(arrayOfFuns[0]());
Expected Output
10
11
12
13
14
15
[ function, function, function, function, function, function ]
10 // console.log(arrayOfFuns[0]());
Output
10
11
12
13
14
15
[ undefined, undefined, undefined, undefined, undefined, undefined ]
/home/moss/var/Modern JS for the Impatient/3.3.js:16
console.log(arrayOfFuns[0]());
^
TypeError: arrayOfFuns[0] is not a function
at Object.<anonymous> (/home/moss/var/Modern JS for the Impatient/3.3.js:16:27)
at Module._compile (internal/modules/cjs/loader.js:1072:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1101:10)
at Module.load (internal/modules/cjs/loader.js:937:32)
at Function.Module._load (internal/modules/cjs/loader.js:778:12)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:76:12)
at internal/main/run_main_module.js:17:47
Why is the arrayOfFuns array element filled with undefined? I thought it would be an array of functions. Also I expected that accessing the first element of arrayOfFuns would print 10.
I think you are looking for something like this.
I have created a function named nf which returns the ith value and pushed it in the array.
function values(f, low, high) {
var result = [];
for(let i = low; i < high; i++) {
f(i);
const nf = () => i;
result.push(nf);
}
return result;
}
const vf = (p1) => console.log(p1);
const arrayOfFuns = values(vf, 10, 16);
console.log(arrayOfFuns);
console.log(arrayOfFuns[0]());You can create an anonymous function each time.
function values(f, low, high) {
var result = [];
for(var i = low; i < high; i++) {
result.push(()=> f(i));
}
return result;
}
const vf = (p1) => console.log(p1);
const arrayOfFuns = values(vf, 10, 16);
console.log(arrayOfFuns);
console.log(arrayOfFuns[0]());