can I give to empty array certain length that, that array will take only that much length of elements. for example:
var emptyArray = []; // but I need this array takes only 10 elements
for (var i = 0; i < 50; i++) {
emptyArray.push(i);
}
console.log(emptyArray.length) // I want to see 10
console.log(emptyArray) // [0,1,2,3,4,5,6,7,8,9]
You can try Object.seal(). Note that in this example, I'm not using push() since that will throw an error, but assigning values since the values in the fixed length Array are mutable
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/seal
var emptyArray = new Array(10).fill(0);
Object.seal(emptyArray);
for (var i = 0; i < 50; i++) {
emptyArray[i] = i;
}
console.log(emptyArray.length) // I want to see 10
console.log(emptyArray) // [0,1,2,3,4,5,6,7,8,9]
Another approach is to use a Proxy:
function limitedArray(length) {
return new Proxy([], {
set: (target, prop, value) => {
if (Number(prop) < length) {
target[prop] = value;
}
return true;
}
});
}
var tenArray = limitedArray(10);
for (let i = 0; i < 50; ++i) {
tenArray.push(i);
}
console.log(Array.from(tenArray)); // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]You can use a different set method instead, if you want it to throw an error when the array’s length is about to be exceeded:
set: (target, prop, value) => {
if(!isNaN(prop) && Number(prop) >= length){
return false;
}
if (Number(prop) < length) {
target[prop] = value;
}
return true;
}
Note though, that handling deletion of elements requires a bit more work.
Not directly as you want, however you can have something similar :
var emptyArray = Array.from({length:50}, (v,i) => undefined);
for(let i=0; i<emptyArray;i++){
emptyArray.push(i);
}
Basically you set up your array with undefined values with a certain length, and then loop until you reach the length.
