Ī data expression is any expression that accesses feature data – that is, any expression that uses one of the data operators: get, has, id, geometry-type, properties, or feature-state. Each argument is either a literal value (a string, number, boolean, or null), or another expression array. Elements that follow (if any) are the arguments to the expression. The first element of an expression array is a string naming the expression operator, for example "*" or "case". Camera operators for providing access to the parameters defining the current map viewĮxpressions are represented as JSON arrays.Data operators for providing access to the properties of source features.String operators for manipulating strings.Logical operators for manipulating boolean values and making conditional decisions.Mathematical operators for performing arithmetic and other operations on numeric values.The expression operators provided by Mapbox GL include: In my case, * 1 is the winner performance-wise 10x faster than other alternatives.You can define the value for any layout property, paint property, or filter as an expression.Īn expression defines a formula for computing the value of the property using the operators described below. Generally one of the fastest options, behaves like the + unary operator, so it does not perform conversion to an integer if the number is a float. Similar to the + unary operator, but returns the integer part, is to use Math.floor(): Math. See how it returns NaN in the first example, which is the correct behavior: it’s not a number. Its parseInt() sibling, it only takes one argument – the string to convert: parseFloat ( '10,000' ) //10 ❌ parseFloat ( '10.00' ) //10 ✅ (considered decimals, cut) parseFloat ( '10.000' ) //10 ✅ (considered decimals, cut) parseFloat ( '10.20' ) //10.2 ✅ (considered decimals) parseFloat ( '10.81' ) //10.81 ✅ (considered decimals) parseFloat ( '10000' ) //10000 ✅ Use + If you want to retain the decimal part and not just get the integer part, use parseFloat(). ParseInt() tries to get a number from a string that does not only contain a number: parseInt ( '10 lions', 10 ) //10īut if the string does not start with a number, you’ll get NaN (Not a Number): parseInt ( "I'm 10", 10 ) //NaNĪlso, just like Number it’s not reliable with separators between the digits: parseInt ( '10,000', 10 ) //10 ❌ parseInt ( '10.00', 10 ) //10 ✅ (considered decimals, cut) parseInt ( '10.000', 10 ) //10 ✅ (considered decimals, cut) parseInt ( '10.20', 10 ) //10 ✅ (considered decimals, cut) parseInt ( '10.81', 10 ) //10 ✅ (considered decimals, cut) parseInt ( '10000', 10 ) //10000 ✅ Other solutions Use parseInt() and parseFloat()Īnother good solution for integers is to call the parseInt() function: const count = parseInt ( '1234', 10 ) //1234ĭon’t forget the second parameter, which is the radix, always 10 for decimal numbers, or the conversion might try to guess the radix and give unexpected results. In the case you need to parse a string with decimal separators, use Intl.NumberFormat instead. If we use the constructor ( new Number("1234")) it returns us a Number object instead of a number value, so pay attention. Number is a wrapper object that can perform many operations. The best one in my opinion is to use the Number object, in a non-constructor context (without the new keyword): const count = Number ( '1234' ) //1234 JavaScript provides various ways to convert a string value into a number. Learn how to convert a string to a number using JavaScript
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