how to check if string is a number js code example

Example 1: javascript check if string is number

// native returns true if the variable does NOT contain a valid number
isNaN(num)

// can be wrapped for making simple and readable
function isNumeric(num){
  return !isNaN(num)
}

isNumeric(123)         // true
isNumeric('123')       // true
isNumeric('1e10000')   // true (This translates to Infinity, which is a number)
isNumeric('foo')       // false
isNumeric('10px')      // false

Example 2: javascript is variable a string

if (typeof myVar === 'string'){
    //I am indeed a string
}

Example 3: javascript check if string is number

function isNumeric(num){
  return !isNaN(num)
}
isNumeric("23.33"); //true, checking if string is a number.

Example 4: js check if string or int

var myString     =  "abc123";
var otherString  =  "123";
/* isInterger() checks if an value repersents an int  */

Number.isInteger(myString);    //returns false
Number.isInteger(otherString); //returns true

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Python Example

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