我正在尝试返回$ ./get_min < input_file > output_file
或true
以确定是否在JavaScript中定义了数组,如下所示: CodePen link
false
我想在//display function object to display stuff
display(value) {
//reset display marker to reset the display
var resetDisplay = false;
//check the arugments if number set it to display or if an operation highlight the function
if (isNaN(value[0]) && value[0] != ".") {
//highlight selected operation
$(id[value]).css("padding", "5px");
//if clear pressed set display to zero
if (value == "=") {
$("#display").text("0");
}
//set reset display to true
resetDisplay = true;
} else {
//display the value by concatenating it unless reset display is set to true after operation pressed
if (resetDisplay = true) {
$("#display").text(value);
//reset the display to not true to continue to concatenate
resetDisplay = false;
} else {
//continue to concatenate display
$("display").text($("#display").text().concat(value));
console.log($("#display").text().concat(value));
}
}
//helper object that correlates with #id for each button
var id = {
"+": "#add",
"-": "#subtract",
"*": "#multiply",
"/": "#divide",
"=": "#equals",
"1": "#one",
"2": "#two",
"3": "#three",
"4": "#four",
"5": "#five",
"6": "#six",
"7": "#seven",
"8": "#eight",
"9": "#nine",
"0": "#zero",
".": "#point"
}
}
无法读取&#39; - &#39;未定义。
我正在尝试从按钮发送操作。此函数在计算器对象中发生。
答案 0 :(得分:0)
您的主要问题在于您检查resetDisplay
变量的方式。通过使用=
运算符,您实际上是将true
分配给resetDisplay
,而不是检查true
。
您可以非常轻松地通过身份(严格相等)true
检查===
,或者只使用if(variableName)
执行以下操作,无论如何都应检查true
。
if (resetDisplay) {
$("#display").text(value);
//reset the display to not true to continue to concatenate
resetDisplay = false;
}
如果您$(id[value])
需要确保id
在之前声明为,则使用它。所以请确保通过声明它来解决这个问题:
//display function object to display stuff
display(value) {
//reset display marker to reset the display
var resetDisplay = false,
id = { //helper object that correlates with #id for each button
"+": "#add",
"-": "#subtract",
"*": "#multiply",
"/": "#divide",
"=": "#equals",
"1": "#one",
"2": "#two",
"3": "#three",
"4": "#four",
"5": "#five",
"6": "#six",
"7": "#seven",
"8": "#eight",
"9": "#nine",
"0": "#zero",
".": "#point"
};
//check the arugments if number set it to display or if an operation highlight the function
if (isNaN(value[0]) && value[0] != ".") {
//highlight selected operation
$(id[value]).css("padding", "5px");
//if clear pressed set display to zero
if (value == "=") {
$("#display").text("0");
}
//set reset display to true
resetDisplay = true;
} else {
//display the value by concatenating it unless reset display is set to true after operation pressed
if (resetDisplay) {
$("#display").text(value);
//reset the display to not true to continue to concatenate
resetDisplay = false;
} else {
//continue to concatenate display
$("display").text($("#display").text().concat(value));
console.log($("#display").text().concat(value));
}
}
}