使用 JavaScript 在计算器上退格
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/30849912/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
提示：将鼠标放在中文语句上可以显示对应的英文。显示中英文
时间：2020-10-28 12:47:45 来源:igfitidea点击:
Backspace on calculator using JavaScript
提问by MrEhawk82
i am making a calculator. But i am having trouble making the backspace button. I found this: Delete last character from input, however I would like to stick with JavaScript only without jquery. Here is what I have so far...
我正在制作一个计算器。但是我在制作退格按钮时遇到了麻烦。我发现了这一点：从 input 中删除最后一个字符，但是我只想坚持使用 JavaScript 而不使用 jquery。这是我到目前为止所拥有的......
HTML
HTML
<div class="box">
<center><div class="display"><input type="text" size="18" id="d" readonly ></div></center>
<div class="keys"><center>
<p><input type="button" class="button grey" value="%" onclick='c("not defined ")'><input type="button" class="button grey" value="√" onclick='c("not defined ")'><input type="button" class="button grey" value="←" onclick='back()'><input type="button" class="button grey" value="/" onclick='math("/")'></p>
<p><input type="button" class="button black" value="7" onclick='math("7")'><input type="button" class="button black" value="8" onclick='math("8")'><input type="button" class="button black" value="9" onclick='math("9")'><input type="button" class="button grey" value="*" onclick='math("*")'></p>
<p><input type="button" class="button black" value="4" onclick='math("4")'><input type="button" class="button black" value="5" onclick='math("5")'><input type="button" class="button black" value="6" onclick='math("6")'><input type="button" class="button grey" value="-" onclick='math("-")'></p>
<p><input type="button" class="button black" value="1" onclick='math("1")'><input type="button" class="button black" value="2" onclick='math("2")'><input type="button" class="button black" value="3" onclick='math("3")'><input type="button" class="button grey" value="+" onclick='math("+")'></p>
<p><input type="button" class="button black" value="0" onclick='math("0")'><input type="button" class="button black" value="." onclick='math(".")'><input type="button" class="button black" value="C" onclick='c("")'><input type="button" class="button green" value="=" onclick='e()'></p>
<center></div>
JavaScript
JavaScript
function c(val) {
document.getElementById("d").value=val;
}
function math(val) {
document.getElementById("d").value+=val;
}
function back() {
//delete last letter function.
}
function e() {
try {
c(eval(document.getElementById("d").value))
}
catch(e) {
c('Error')
}
}
回答by Juank
function back() {
var value = document.getElementById("d").value;
document.getElementById("d").value = value.substr(0, value.length - 1);
}
