我有问题添加一个数组的所有元素以及平均它们。我将如何做到这一点，并实现它与我目前的代码?元素的定义如下所示。
<script type="text/javascript">
//<![CDATA[
var i;
var elmt = new Array();
elmt[0] = "0";
elmt[1] = "1";
elmt[2] = "2";
elmt[3] = "3";
elmt[4] = "4";
elmt[5] = "7";
elmt[6] = "8";
elmt[7] = "9";
elmt[8] = "10";
elmt[9] = "11";
// Problem here
for (i = 9; i < 10; i++){
document.write("The sum of all the elements is: " + /* Problem here */ + " The average of all the elements is: " + /* Problem here */ + "<br/>");
}
//]]>
</script>
当前回答
我在我的个人库中使用这些方法:
Array.prototype.sum = Array.prototype.sum || function() {
return this.reduce(function(sum, a) { return sum + Number(a) }, 0);
}
Array.prototype.average = Array.prototype.average || function() {
return this.sum() / (this.length || 1);
}
编辑: 要使用它们，只需询问数组的和或平均值，如下所示:
[1,2,3].sum() // = 6
[1,2,3].average() // = 2
其他回答
似乎有无数的解决方案，但我发现这个是简洁和优雅的。
const numbers = [1,2,3,4];
const count = numbers.length;
const reducer = (adder, value) => (adder + value);
const average = numbers.map(x => x/count).reduce(reducer);
console.log(average); // 2.5
或者更简洁地说:
const numbers = [1,2,3,4];
const average = numbers.map(x => x/numbers.length).reduce((adder, value) => (adder + value));
console.log(average); // 2.5
根据您的浏览器，您可能需要执行显式函数调用，因为箭头函数不受支持:
const r = function (adder, value) {
return adder + value;
};
const m = function (x) {
return x/count;
};
const average = numbers.map(m).reduce(r);
console.log(average); // 2.5
Or:
const average1 = numbers
.map(function (x) {
return x/count;
})
.reduce(function (adder, value) {
return adder + value;
});
console.log(average1);
只是为了好玩:
var elmt = [0, 1, 2,3, 4, 7, 8, 9, 10, 11], l = elmt.length, i = -1, sum = 0;
for (; ++i < l; sum += elmt[i])
;
document.body.appendChild(document.createTextNode('The sum of all the elements is: ' + sum + ' The average of all the elements is: ' + (sum / l)));
var scores =[90, 98, 89, 100, 100, 86, 94];
var sum = 0;
var avg = 0;
for(var i = 0; i < scores.length;i++){
//Taking sum of all the arraylist
sum = sum + scores[i];
}
//Taking average
avg = sum/scores.length;
//this is the function to round a decimal no
var round = avg.toFixed();
console.log(round);
我认为一个更优雅的解决方案:
const sum = times.reduce((a, b) => a + b, 0);
const avg = (sum / times.length) || 0;
console.log(`The sum is: ${sum}. The average is: ${avg}.`);
将for循环计数器设置为0....你得到了元素9，然后你就完成了。其他答案都是基础数学。使用一个变量来存储你的和(需要将字符串转换为整数)，然后除以你的数组长度。
