currently encountered a problem:
it is known that the length of the array is 5, there may be one, two or more values in the array, and the rest of the values want to be filled with "0".
in addition to the methods of the for loop, js has no native methods for arrays to do this.
var arr = new Array(20);
arr[2] = 1;
arr[18] =2 ;
var r = Array.from(arr,(elem) => elem = elem === undefined ? 0 : elem);try to see if it's what you want
ES5
var arr = new Array(20);
arr[2] = 1;
arr[18] =2 ;
arr = JSON.parse(JSON.stringify(arr)).map(function (elem) {
return elem = elem === null ? 0 : elem
});
console.log(arr);look at
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