I need a way to check if an array only contains numbers. For example
var a = [1,2,3,4] should pass and give true boolean
whereas var b = [1,3,4,'a'] should give false
I tried forEach() function as
a.forEach(function(item, index, array) {
if(!isNaN(item)) {
array.unshift("-");
}
}); //console.log of this will give array a = ["-","-","-","-", 1,2,3,4]
but since, forEach() iterates through every index in the array, and since every item for var a is a number, it unshifts to array every item it iterates. I need a way to only unshift "-" once if the whole array value is a number.
I also tried to do with test()
var checkNum = /[0-9]/;
console.log(checkNum.test(a)) //this gives true
console.log(checkNum.test(b)) // this also gives true since I believe test
//only checks if it contains digits not every
//value is a digit.
最简单的方法是使用Array
的every
函数:
var res = array.every(function(element) {return typeof element === 'number';});
Try something like this:
var a = arr.reduce(function(result, val) {
return result && typeof val === 'number';
}, true);
function areNumbers(arr) { document.write(JSON.stringify(arr) + ':') return arr.reduce(function(result, val) { return result && typeof val === 'number'; }, true); } document.write(areNumbers([1, 2, 3, 4]) + '<br>'); document.write(areNumbers([1, 2, 3, '4']) + '<br>');
var filteredList = a.filter(function(item){ return !isNaN(+item) });
开头的+号将尝试将项目的内容转换为数字,如果可以的话,则不会将其过滤掉,例如:
var numbers = +"123"
console.log(numbers) //will print out 123 as numbers not as a string
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