试图将数字保留在只有 5 位数字和只有数字 2,3,5,7 的数组中

Question

我试图摆脱产品数组中没有质数或没有 5 位数字的所有数字。在最后一个 for 循环中拼接它们之后，products 数组仍然有不满足我的 if 条件的数字。let arr1 = [222, 223, 225 ,227, 232, 233, 235, 237,252, 253, 255, 257, 272, 273, 275, 277, 322, 323, 325, 327, 332, 333, 335, 337, 352, 353, 355, 357, 372, 373, 375, 377, 522, 523, 525, 527, 532, 533, 535, 537, 552,553,555, 557, 572, 573, 575, 577, 722, 723, 725, 727, 732, 733, 735, 737, 752, 753, 755, 757, 772, 773, 775, 777]let arr2 = [22, 23, 25, 27, 32, 33,35, 37, 52, 53, 55, 57, 72, 73, 75,77]products = []  for (var i=0; i< arr1.length; i++){  for (var j=0; j< arr2.length; j++){    products.push(arr1[i]*arr2[j])  }}// console.log(products.length);function not_prime(num){  var str1 = num.toString()  if (     str1.indexOf(2) > -1 ||     str1.indexOf(3) > -1 ||     str1.indexOf(5) > -1 ||     str1.indexOf(7) > -1 ||    str1.length != 5) {    return false;    }  return true;}for (var i=0; i< products.length; i++){  if (not_prime(products[i])) {    products.splice(i, 1);  }}console.log(products)

Answer 1

问题不是很清楚，但是看看这个：

const arr1 = [222, 223, 225 ,227, 232, 233, 235, 237,252, 253, 255, 257, 272, 273, 275, 277, 322, 323, 325, 327, 332, 333, 335, 337, 352, 353, 355, 357, 372, 373, 375, 377, 522, 523, 525, 527, 532, 533, 535, 537, 552,553,555, 557, 572, 573, 575, 577, 722, 723, 725, 727, 732, 733, 735, 737, 752, 753, 755, 757, 772, 773, 775, 777];

const arr2 = [22, 23, 25, 27, 32, 33,35, 37, 52, 53, 55, 57, 72, 73, 75,77];

const products = [];

arr1.forEach(q => {

  arr2.forEach(v => {

    let n = q*v, s = n.toString();

    if(s.length === 5 && s.match(/^[2357]+$/))products.push(n);

  });

});

console.log(products);

Answer 2

使用Array.filter()和Array.some这里。请参阅内联评论。

let arr1 = [222, 223, 225 ,227, 232, 233, 235, 237,252, 253, 255, 257, 272, 273, 275, 277, 322, 323, 325, 327, 332, 333, 335, 337, 352, 353, 355, 357, 372, 373, 375, 377, 522, 523, 525, 527, 532, 533, 535, 537, 552,553,555, 557, 572, 573, 575, 577, 722, 723, 725, 727, 732, 733, 735, 737, 752, 753, 755, 757, 772, 773, 775, 777]

let arr2 = [22, 23, 25, 27, 32, 33,35, 37, 52, 53, 55, 57, 72, 73, 75,77];

let primes = [2,3,5,7];

products = []  

for (var i=0; i< arr1.length; i++){

  for (var j=0; j< arr2.length; j++){

    products.push(arr1[i]*arr2[j])

  }

}

// Return a filtered array of products that only contains

// items from the original array that pass the provided callback

// function's tests.

let results = products.filter(function(item){

    // Test to see if item contains primes

    let prime = Array.from(item.toString()).some(function(char){

      return primes.indexOf(+char);

    });

    // Return item only if contains a prime and has 5 digits

    return prime && item.toString().length === 5 ? item : null;

});

console.log(results);