In Javascript what is the method to allow integer and float but not chars

Question

In my javascript variable I am getting the value as "abc" or "123" or "123.456" based on the input given in the input field. For all the values the type is string even if the entered value is number or float.

typeof(variable) gives string always.

The following method will be triggered on each keydown . I am also using the lodash library

convertMethod(val) {
    console.log(round(val,2).toString())    //round is a lodash method which is imported already
}

When I round the value the decimal point is not coming. I just want to round the value by two decimal points if the entered value is digits and not alphabets. How can I fix this?

Answer 1

You can check if it number or not using isNaN . Round it up if it is a number:

convertMethod(val) {
    if(!isNaN(val))
       console.log(round(val,2).toString())
    else
       console.log(val)
}

convertMethod("qw")
convertMethod("12.3456")
convertMethod("12.432")
convertMethod("12")

Output:

"qw"
"12.35"
"12.43"
"12"

Answer 2

Try converting the string to a number (via _.toNumber() or the + operator. Then check if it's a number using _.isFinite() which returns false for non numbers, Infinite, -Infinite, and NaN .

 const { isFinite, round } = _ const convertMethod = val => { if (isFinite(+val)) console.log(round(val, 2).toString()) else console.log(val) } convertMethod('5.4435') convertMethod('abc')

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>