[英]Enable/Disable textbox and button using JavaScript
我正在学习 JavaScript,需要在完成 for 循环并显示未来值后禁用文本框(年利率)。 我还需要修改 clear_click 事件,以便在单击清除按钮时启用文本框,这是我的代码:
var $ = function (id) {
return document.getElementById(id);
}
var calculate_click = function () {
var investment = parseFloat( $("investment").value );
var annualRate = parseFloat( $("rate").value );
var years = parseInt( $("years").value );
$("futureValue").value = "";
if (isNaN(investment) || investment <= 0) {
alert("Investment must be a valid number\nand greater than zero.");
} else if(isNaN(annualRate) || annualRate <= 0) {
alert("Annual rate must be a valid number\nand greater than zero.");
} else if(isNaN(annualRate) || annualRate >= 20) {
alert("Annual rate must be a valid number\nand less than twenty.");
} else if(isNaN(years) || years <= 0) {
alert("Years must be a valid number\nand greater than zero.");
} else if(isNaN(years) || years >= 50) {
alert("Years must be a valid number\nand less than fifty.");
} else {
var monthlyRate = annualRate / 12 / 100;
var months = years * 12;
var futureValue = 0;
for ( i = 1; i <= months; i++ ) {
futureValue = ( futureValue + investment ) *
(1 + monthlyRate);
}
$("futureValue").value = futureValue.toFixed(2);
}
}
var clear_click = function () {
$("investment").value = "";
$("rate").value = "";
$("years").value = "";
$("futureValue").value ="";
}
window.onload = function () {
$("calculate").onclick = calculate_click;
$("investment").focus();
$("clear").onclick = clear_click;
}
您可以使用 JQuery:
$('#textbox').attr('disabled', 'disabled');
并再次启用它:
$('#textbox').removeAttr("disabled");
或者使用纯 JavaScript:
禁用:
document.getElementById("textboxId").setAttribute("disabled", "disabled");
使能够:
document.getElementById("textboxId").removeAttribute("disabled");
看来您还没有使用任何库,所以让我们使用基本的 Javascript。
您可以查看一些库,如jQuery (玩 DOM 操作)和/或lodash (帮助进行集合操作)来帮助您。
要在纯 javascript 中使用 DOM 输入元素的disabled
属性,请查看此 jsfiddle: http : //jsfiddle.net/arnaudj/nrnyo4e9/
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