javascript - 如何检查值是否是数字

Question

如何检查 value 是否为数字。如果它是数字值，则显示文本居中，否则显示文本左侧。我想知道我的说法有什么问题。

 for (var l = 0; l < Object.keys(pods[i].data.summaryDetailedData).length; l++) {
    contentHtml += "<tr>";

    for (var m = 0; m < pods[i].data.columns.length; m++) {

        for (var field in pods[i].data.summaryDetailedData[l]) {
            var rowspan = (pods[i].data.summaryDetailedData[l].children !== undefined ? pods[i].data.summaryDetailedData[l].children.length : "");
            rowspanMax = Math.max(rowspanMax, rowspan);

            if (field === pods[i].data.columns[m]) {

                var preFix = pods[i].data.summaryDetailedData[l]["sPrefix"] !== undefined ? pods[i].data.summaryDetailedData[l]["sPrefix"] : "";
                var postFix = pods[i].data.summaryDetailedData[l]["sPostfix"] !== undefined ? pods[i].data.summaryDetailedData[l]["sPostfix"] : "";
                var value = pods[i].data.summaryDetailedData[l][field];
                if (value.toString().substr(0, 3) == "- 1") {
                    value = "N/A";
                }
                var color = pods[i].data.summaryDetailedData[l][field + "_color"];
                if (colName[m] === "sLabel" && pods[i].data.summaryDetailedData[l].bStepThrough == true) {
                    value = "<a href=\"#\" class=\"stepthrough\">" + value + "</a>";
                }
                color = color !== "" && color !== undefined ? " <span class=\"color\" style=\"background: #" + color + "\"></span>" : " <span class=\"color\"></span>";
                contentHtml += "<td rowspan1=\"" + 1 + "\" class=\"" + (rowspan !== "" && rowspan > 1 ? "groups" : "") + " " + (!isNaN(value) || (!isNaN(value.toString().substr(1, value.length)) || value == "N/A" || typeof value == Number) ? "text-center" : "text-left") + "\">" + value + (Number(value) ? preFix : "") + color + (!isNaN(value) ? postFix : "") + "</td>";
                if (rowspan > 1) {
                    var rowspanContent = "<td rowspa1=\"" + rowspan + "\" class=\"" + (rowspan !== "" && rowspan > 1 ? "groups" : "") + " " + (!isNaN(value) || (!isNaN(value.toString().substr(1, value.length)) || value == "N/A" || typeof value == Number) ? "text-center" : "text-left") + "\">" + value + (Number(value) ? preFix : "") + color + (!isNaN(value) ? postFix : "") + "</td>";
                }

                if (field === "sLabel") {
                    for (var child in pods[i].data.summaryDetailedData[l].children) {

                        if (child > 0 && rowspan >= 2) {
                            contentHtml += "</tr>";
                            contentHtml += "<tr>";
                            contentHtml += rowspanContent;
                        }

Answer 1

您使用typeof:

var ff=1.222; console.log(typeof ff) // number
(typeof ff == "number") // true
var ff="1.222"; console.log(typeof ff) // string
(typeof ff == "number") // false

或

使用toFixed方法，如果变量不是数字，则返回undefined，否则，数字对象将在其原型(prototype)中定义函数，因此它将返回函数 toFixed 本身，因此它是一个数字。

(this is sort of a hack, but it is efficient and least cost)

contentHtml += "<td class=\"" 
  +  (value.toFixed) ? "text-center" : "text-left" + "\">" ) 
  + value + (value.toFixed) ? preFix : "" 
  + color + (value.toFixed) ? postFix : "" + "</td>";