Question

我想将数组中的数字更改为百分比，但我不确定如何执行此操作。

var nums = [84394, 78952, 65570, 58097, 55673, 41847, 24884, 16567, 9966, 1689];

应该是：

var results = [84, 78, 65, 58, 55, 41, 24, 16, 9, 1]

我的尝试：

var nums = [84394, 78952, 65570, 58097, 55673, 41847, 24884, 16567, 9966, 1689];
var results = [];

for (var i = 0; i < nums.length; i++) {
  var percentage = Math.floor(nums[i] / 100);
  results.push(percentage).toFixed(2);
}

document.write(results.join(", "));

Answer 1

阅读Array.prototype.map和Bitwise OR (|)。

var nums = [84394, 78952, 65570, 58097, 55673, 41847, 24884, 16567, 9966, 1689];

var convertToPercentages = function (arr, max) {
    return nums.map(function (d, i) {
        // time for some math
        // we know the max is n
        // so, to produce a whole-number percent
        // we need to divide each digit `d` by `max`,
        // then multiply by 100
        // we then (`| 0`) to remove the decimals (same as Math.floor)
        return (100 * d / max) | 0;
    });
}

更好的方法（确定自己的最大值）：

var getNearestPowerOfTen = function (arr) {
    var max = arr.reduce(function (p, c) {
        // is the previous less than the current item?
        // if so, then return the current item
        // otherwise, return the previous item
        return p < c ? c : p;
    }, 0);
    // to find the next highest power of 10,
    // we should return 10 raised to the number of digits
    // in the integer part of our number
    return Math.pow(10, (max | 0).toString().length);
}

var convertToPercentages2 = function (arr) {
    var max = getNearestPowerOfTen(arr);
    return nums.map(function (d, i) {
        return (100 * d / max) | 0;
        // could be more efficient with just
        // `(d / max) | 0`, if you divide `max` by 100 above
    });
}

更好的方法（因为我们无论如何都在做数学）

var getNearestPowerOfTen2 = function (arr) {
    var max = arr[0];
    // for-loop is faster than `Array.prototype.reduce`
    for (var i = 1; i < arr.length; i++) {
        if (max < arr[i]) max = arr[i];
    }
    return Math.pow(10, Math.ceil(Math.log10(max)));
}

Answer 2

这应该有效：

var nums = [84394, 78952, 65570, 58097, 55673, 41847, 24884, 16567, 9966, 1689];
var results = [];


for(var i = 0; i < nums.length; i++) {
  var divideBy = 0;
  if ( nums[i] < 10000 )
     divideBy = 100;
  else if ( nums[i] < 100000 )
     divideBy = 1000;
  else if ( nums[i] < 1000000 )
     divideBy = 10000;
  else if ( nums[i] < 10000000 )
     divideBy = 100000;
  else if ( nums[i] < 100000000 )
     divideBy = 1000000;
  var percentage = Math.floor(nums[i] / divideBy);

  results.push( percentage.toFixed(2) );
}

console.log(results);

Answer 3

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

  var percentage = parseInt((nums[i] + '').slice(0,2));

  results.push( percentage );
}

Answer 4

根据您的问题（所需结果），您的所有数字看起来都是3个精确浮点数乘以1000.

如果您希望根据下一个sig数字舍入结果：

＆＃13;

/contacts/24552

＆＃13;

如果您只想要前两位数字：

＆＃13;

var nums = [84394, 78952, 65570, 58097, 55673, 41847, 24884, 16567, 9966, 1689];

function roundedPercents(n){
  return (n/1000).toFixed(0);
}
var roundedResults = nums.map(roundedPercents);
document.write(roundedResults.join(", "));

＆＃13;

将数字更改为数组中的百分比

4 个答案: