如何检查数组中是否存在NaN关键字?[副本]

对我来说这有效吗??

for (i=0; i < arr.length; i++){

    // check if array value is false or NaN
    if (arr[i] === false || Number.isNaN(arr[i]) ) {
        console.log("NaN");
    }

  }

你可以检查一下类型( typeof NaN === 'number' )和 isNaN 对于 NaN 价值

var arr = [7, 1, "abc", undefined, NaN], i;
for (i = 0; i < arr.length; i++){
    if (typeof arr[i] === 'number' && isNaN(arr[i])) {
        console.log('Element ' + i + ' is NaN');
    }
}

或 check if the value is unequal to itself .

var arr = [7, 1, "abc", undefined, NaN], i;
for (i = 0; i < arr.length; i++){
    if (arr[i] !== arr[i]) {
        console.log('Element ' + i + ' is NaN');
    }
}

在ECMAScript 6中,您可以使用数字。isNaN函数:

var arr = [7, 1, "abc", undefined, NaN];

for (i=0; i < arr.length; i++){

    // check if array value is false or NaN
    if (arr[i] === false || Number.isNaN(arr[i])) {
        console.log("NaN found at place " + i);
    }

  }

如果需要在ECMAScript 5中工作,那么isNaN函数的问题是它正在检查该值是否能够强制转换为数字。相反,您可以使用NaN值的奇数属性-它不等于自身:

var arr = [7, 1, "abc", undefined, NaN];

for (i=0; i < arr.length; i++){

    // check if array value is false or NaN
    if (arr[i] === false || arr[i] != arr[i]) {
        console.log("NaN found at place " + i);
    }

  }

isNan为我工作:

for (i=0; i < arr.length; i++){
    // check if array value is false or NaN
    if (isNaN(arr[i])) {
        console.log("Not a number at index " + i + ": "+arr[i]);
    }
}

打印(在node.js中):

Not a number at index 2: abc
Not a number at index 3: undefined
Not a number at index 4: NaN

首先将值转换为String。然后检查 value == 'NaN'

for (i=0; i < arr.length; i++){

    // check if array value is false or NaN
    if (arr[i] === false || (arr[i] != undefined && typeof(arr[i]) == "number" && arr[i].toString() === 'NaN')) {
        // do something
    }

  }