[英]Javascript: Calculating Min/Max/Average
我在Java站点的html站点中编写了此代码,但工作不正常。 大多数情况下,它似乎忽略了一些条目,只是随机选择最小/最大值。 另外,当我尝试计算平均值时,即使变量在开始时声明为0,我还是得到了一个字符串而不是一个数字。 例如,执行0 + 1 + 1 + 2 + 3 + 5 = 011235而不是12。这是代码,在此先感谢。
**编辑:我在最后添加了学生平均代码,但是它不起作用,它在页面上甚至“学生” + [i]部分都没有显示任何结果。 另一方面,parseInt()命令起作用了,并使一切正常工作了,谢谢:)
<script language = "javascript">
function myFunction() {
var course0 = [];
var course1 = [];
var course2 = [];
var minstugrade = 100;
var maxstugrade = 0;
var minstugradetext = "";
var maxstugradetext = "";
var stuavgarr = [];
var minstuavg = 100;
var maxstuavg = 0;
var minstuavgtext = "";
var maxstuavgtext = "";
var mincougrade = 100;
var maxcougrade = 0;
var mincougradetext = "";
var maxcougradetext = "";
var mincouavg = 100;
var maxcouavg = 0;
var mincouavgtext = "";
var maxcouavgtext = "";
var couavg = 0;
//add form items to array
var x = document.getElementById("course0");
var i;
for (i = 0; i < x.length ;i++) {
course0.push(parseInt(x.elements[i].value));
}
var x = document.getElementById("course1");
var i;
for (i = 0; i < x.length ;i++) {
course1.push(parseInt(x.elements[i].value));
}
var x = document.getElementById("course2");
var i;
for (i = 0; i < x.length ;i++) {
course2.push(parseInt(x.elements[i].value));
}
//calculate course & student min/max
for (i = 0; i < course0.length; i++) {
if (course0[i] < mincougrade) {
mincougrade = course0[i];
mincougradetext = "course0";
}
if (course0[i] > maxcougrade) {
maxcougrade = course0[i];
maxcougradetext = "course0";
}
if (course0[i] < minstugrade) {
minstugrade = course0[i];
minstugradetext = "student" + [i];
}
if (course0[i] > maxstugrade) {
maxstugrade = course0[i];
maxstugradetext = "student" + [i];
}
}
for (i = 0; i < course1.length; i++) {
if (course1[i] < mincougrade) {
mincougrade = course1[i];
mincougradetext = "course1";
}
if (course1[i] > maxcougrade) {
maxcougrade = course1[i];
maxcougradetext = "course1";
}
if (course1[i] < minstugrade) {
minstugrade = course1[i];
minstugradetext = "student" + [i];
}
if (course1[i] > maxstugrade) {
maxstugrade = course1[i];
maxstugradetext = "student" + [i];
}
}
for (i = 0; i < course2.length; i++) {
if (course2[i] < mincougrade) {
mincougrade = course2[i];
mincougradetext = "course2";
}
if (course2[i] > maxcougrade) {
maxcougrade = course2[i];
maxcougradetext = "course2";
}
if (course2[i] < minstugrade) {
minstugrade = course2[i];
minstugradetext = "student" + [i];
}
if (course2[i] > maxstugrade) {
maxstugrade = course2[i];
maxstugradetext = "student" + [i];
}
}
//calculate course average
for (i = 0; i < course0.length; i++) {
couavg += course0[i];
}
couavg = couavg / course0.length
if (couavg < mincouavg) {
mincouavg = couavg;
mincouavgtext = "course0";
}
if (couavg > maxcouavg) {
maxcouavg = couavg;
maxcouavgtext = "course0";
}
couavg = 0;
for (i = 0; i < course1.length; i++) {
couavg += course1[i];
}
couavg = couavg / course1.length
if (couavg < mincouavg) {
mincouavg = couavg;
mincouavgtext = "course1";
}
if (couavg > maxcouavg) {
maxcouavg = couavg;
maxcouavgtext = "course1";
}
couavg = 0;
for (i = 0; i < course2.length; i++) {
couavg += course2[i];
}
couavg = couavg / course2.length
if (couavg < mincouavg) {
mincouavg = couavg;
mincouavgtext = "course2";
}
if (couavg > maxcouavg) {
maxcouavg = couavg;
maxcouavgtext = "course2";
}
//calculate student average
for (i = 0; i < course0.length; i++) {
stuavgarr[i] += course0[i];
stuavgarr[i] += course1[i];
stuavgarr[i] += course2[i];
}
for (i=0; i < stuavgarr.length; i++) {
stuavgarr[i] = stuavgarr[i] / course0.length;
if (stuavgarr[i] < minstuavg) {
minstuavg = stuavgarr[i];
minstuavgtext = "student" + [i];
}
if (stuavgarr[i] > maxstuavg) {
maxstuavg = stuavgarr[i];
maxstuavgtext = "student" + [i];
}
}
document.getElementById("studmaxgrade").innerHTML = "Student that achieved the max grade is " + maxstugradetext
document.getElementById("studmingrade").innerHTML = "Student that achieved the min grade is " + minstugradetext
document.getElementById("studmaxavg").innerHTML = "Student that achieved the max average is " + maxstuavgtext
document.getElementById("studminavg").innerHTML = "Student that achieved the min average is " + minstuavgtext
document.getElementById("courmaxgrade").innerHTML = "The course in which the max grade is scored is " + maxcougradetext
document.getElementById("courmingrade").innerHTML = "The course in which the min grade is scored is " + mincougradetext
document.getElementById("courmaxavg").innerHTML = "The course in which the max average grade is scored is " + maxcouavgtext
document.getElementById("courminavg").innerHTML = "The course in which the min average grade is scored is " + mincouavgtext
}
</script>
输入的值是一个字符串,因此a + b将被解释为将一个字符串附加到另一个字符串。
如果确保第一个参数(在这种情况下为a)是整数,则a + b将导致两个参数在数学上相加
console.log( '0' + 1 + 2 + 3 + 4 ); //* outputs 01234
console.log( parseInt( 0 ) + 1 + 2 + 3 + 4 ); //* outputs 10
首先,您似乎对document.getElementById感到非常困惑
这根本无法解决javascript变量......
这实际上是“通过其ID获取文档元素”。 这是一个使用方法的例子...
<html>
<img id='my_new_selfie' src='me.jpg'>
....
....
<script>
alert (document.getElementById('my_new_selfie').src)
</script>
这将简单地弹出一个警报,其中包含描述id为'my_new_selfie'的文档对象的src的文本。
[me.txt]
将document.getElementById引入javascript的原因是为了节省开发人员学习DOM(文档对象模型)的权限,以便访问对象。 它允许您简单地给您一个对象id并使用该id对其进行更改
在上面的示例中,我可以使用脚本或按钮来更改图像源,例如,可以使用页面上另一个对象的onclick事件,例如按钮...
onclick='document.getElementById('my_new_selfie').src='new_pic_of_me.JPG'
它不用于标识javascript中的变量
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