我有一个练习，可以使用Javascript执行简单计算。该代码在Visual Studio中工作正常，但在我必须在其中进行练习的Hackerrank测试站点中无法正常工作。
HTML代码：（已经给出，无法修改）：
<HEAD>
<TITLE> Simple Calculation</TITLE>
</HEAD>
<BODY>
<FORM NAME="myForm">
<TABLE BORDER=2>
<TR>
<TD align="center">
<INPUT TYPE="text" ID="screen" NAME="screen" style="width:99%"><br>
</TD>
</TR>
<TR>
<TD>
<INPUT TYPE="button" NAME="7" VALUE=" 7 " onclick="update(7)">
<INPUT TYPE="button" NAME="8" VALUE=" 8 " onclick="update(8)">
<INPUT TYPE="button" NAME="9" VALUE=" 9 " onclick="update(9)">
<INPUT TYPE="button" NAME="+" VALUE=" + " onclick="update('+')">
<br>
<INPUT TYPE="button" NAME="4" VALUE=" 4 " onclick="update(4)">
<INPUT TYPE="button" NAME="5" VALUE=" 5 " onclick="update(5)">
<INPUT TYPE="button" NAME="6" VALUE=" 6 " onclick="update(6)">
<INPUT TYPE="button" NAME="-" VALUE=" - " onclick="update('-')">
<br>
<INPUT TYPE="button" NAME="1" VALUE=" 1 " onclick="update(1)">
<INPUT TYPE="button" NAME="2" VALUE=" 2 " onclick="update(2)">
<INPUT TYPE="button" NAME="3" VALUE=" 3 " onclick="update(3)">
<INPUT TYPE="button" NAME="*" VALUE=" x " onclick="update('*')">
<br>
<INPUT TYPE="button" NAME="c" VALUE=" c " onclick="form_reset();">
<INPUT TYPE="button" NAME="0" VALUE=" 0 " onclick="update(0)">
<INPUT TYPE="button" NAME="=" VALUE=" = " onclick="result();">
<INPUT TYPE="button" NAME="/" VALUE=" / " onclick="update('/')">
</TD>
</TR>
</TABLE>
</FORM>
<script type="text/javascript" src="index.js"></SCRIPT>
</BODY>
</HTML>
JS文件。我无法删除各种功能或添加新功能
var text = "";
function update(value) {
//Type the code here.
text+= value;
document.getElementById('screen').value = value;
}
function result() {
//Type the code here.
document.getElementById('screen').value = eval(text);
}
function form_reset() {
//Type the code here.
document.getElementById('screen').value ="";
text = "";
}
我运行测试时，将针对以下测试用例进行验证。函数result（）失败；同时添加7和8
describe('Calc Handson', function() {
beforeEach(function() {
document.body.innerHTML='<TABLE BORDER=2 id="app"><TR><TD align="center"><INPUT TYPE="text" ID="screen" NAME="screen" style="width:99%"><br> </TD> </TR> <TR><TD> <INPUT TYPE="button" NAME="7" VALUE=" 7 " onclick="update(7)"> <INPUT TYPE="button" NAME="8" VALUE=" 8 " onclick="update(8)"><INPUT TYPE="button" NAME="9"VALUE=" 9 " onclick="update(9)"><INPUT TYPE="button" NAME="+" VALUE=" + " onclick="update("+")"><br><INPUT TYPE="button" NAME="4" VALUE=" 4 " onclick="update(4)"> <INPUTTYPE="button" NAME="5" VALUE=" 5 " onclick="update(5)"><INPUT TYPE="button" NAME="6" VALUE=" 6 " onclick="updat(6)"> <INPUT TYPE="button" NAME="-" VALUE=" - " onclick="update("-")"><br><INPUTTYPE="button" NAME="1" VALUE=" 1 " onclick="update(1)"> <INPUT TYPE="button" NAME="2" VALUE=" 2 " onclick="update(2)"><INPUT TYPE="button" NAME="3" VALUE=" 3 " onclick="update(3)"> <INPUT TYPE="button" NAME="*"VALUE=" x " onclick="update("*")"><br> <INPUT TYPE="button" NAME="c" VALUE=" c "onclick="form_reset();"> <INPUT TYPE="button" NAME="0" VALUE=" 0 " onclick="update(0)"> <INPUT TYPE="button" NAME="=" VALUE=" = " onclick="result();"><INPUT TYPE="button" NAME="/" VALUE=" / " onclick="update("/")"> </TD></TR> </TABLE>';
});
afterEach(function() {
document.body.removeChild(document.getElementById('app'));
});
describe('Calc ', function() {
it('update function should exist', function() {
update(1);
expect(document.getElementById("screen").value).toBe('1');
});
it('update function should exist', function() {
update(2);
expect(document.getElementById("screen").value).toBe('2');
});
it('update function should exist', function() {
update(3);
expect(document.getElementById("screen").value).toBe('3');
});
it('update function should exist', function() {
update(4);
expect(document.getElementById("screen").value).toBe('4');
});
it('update function should exist', function() {
update(5);
expect(document.getElementById("screen").value).toBe('5');
});
it('update function should exist', function() {
update(6);
expect(document.getElementById("screen").value).toBe('6');
});
it('update function should exist', function() {
update(7);
expect(document.getElementById("screen").value).toBe('7');
});
it('update function should exist', function() {
update(8);
expect(document.getElementById("screen").value).toBe('8');
});
it('update function should exist', function() {
update(9);
expect(document.getElementById("screen").value).toBe('9');
});
it('update function should exist', function() {
update(0);
expect(document.getElementById("screen").value).toBe('0');
});
it('update function should exist', function() {
update('*');
expect(document.getElementById("screen").value).toBe('*');
});
it('update function should exist', function() {
update('+');
expect(document.getElementById("screen").value).toBe('+');
});
it('update function should exist', function() {
update('-');
expect(document.getElementById("screen").value).toBe('-');
});
it('update function should exist', function() {
update('/');
expect(document.getElementById("screen").value).toBe('/');
});
it('result function should exist', function() {
update(7);
update('+');
update(8);
result();
expect(document.getElementById("screen").value).toBe('15');
});
it('form_reset function should exist', function() {
update(7);
form_reset();
expect(document.getElementById("screen").value).toBe('');
});
});
});
我遇到的错误是：
Node.js (linux; U; rv:v8.9.4) Calc Handson Calc result function should exist FAILED
SyntaxError: Invalid regular expression: missing /
at result (app/index.js:10:52)
at UserContext.<anonymous> (test/index_test.js:88:6)
Node.js (linux; U; rv:v8.9.4): Executed 16 of 16 (1 FAILED) (0.175 secs / 0.178 secs)
请帮助。
答案 0 :(得分：1)
问题是您的变量text没有在测试套件的不同测试之间重置。测试套件仅重置HTML，而不重置您可能使用的全局变量。尽管将表达式存储在变量中的想法很棒，但是您需要一种不依赖于全局变量的方法。
因此，想法可能是将表达式存储在screen元素中（而不仅仅是输入的最后一个数字）
这就是为什么：
function update(value) {
document.getElementById('screen').value += value;
}
function result() {
document.getElementById('screen').value = eval(document.getElementById('screen').value);
}
function form_reset() {
document.getElementById('screen').value = "";
}