Delayed evaluation for string formatting

python f-string
python lazy string formatting
python string format

I am building up a constants.js file with URLs used in my ReactJS project. These strings include query parameters that can be used with the URL. However, the values used in these strings are only available in a component where the string is used, not in the constants file itself. So for example, I want something like this:

export const BASE_URL = 'https://example.com';
export const FOO_QUERY = '?foo=%s';

where %s is just a placeholder that can be replaced later in a component. (I borrowed printf() syntax from C here for illustration purposes.) What is the correct syntax to do something like this in JavaScript? Is it even possible?


I'd probably use a template literal in a function: The component calls the function with the foo value:

export const fooQuery = foo => `?foo=${foo}`;

Usage:

const query = fooQuery("foo value");

I'd probably use a template literal in a function: The component calls the function with the foo value: export const fooQuery = foo => `?foo=${foo}`;. Usage: I want to be able to use the formatted result as a string, either assign it to a variable or use it in a function call. – Code-Apprentice Oct 13 '18 at 18:12 Then probably crowder's answer is useful.


With tagged template literals you could do:

 function query(parts, ...pos) {
   return apply(...args) {
     return parts.map((part, i) => part + args[ pos[i] ]).join("");
   }
}

Usable as:

 const find = query`?name=${0}&fullname=${0}&age=${1}`;

 console.log(find("jonas", 18));

DE DE(string) DE( ) (for delay evaluation) is used with the Evaluate() and IIF( ) DecimalFormat(number) Returns number as a string formatted to two decimal  When an interpolated string is resolved to a result string, items with interpolation expressions are replaced by the string representations of the expression results. This feature is available starting with C# 6. String interpolation provides a more readable and convenient syntax to create formatted strings than a string composite formatting feature. The following example uses both features to produce the same output:


let string = 'bar';
console.log("Foo %s", string);
var teststr = (string) => `Foo ${string}`; //result: Foo bar

translated string properly formatted for the user's locale before being displayed in the web interface. In this way, final evaluation of rules data could be delayed  Here Mudassar Ahmed Khan has explained with an example, how to use string.Format function with Eval (DataBinder.Eval) function in ASP.Net with C# and VB.Net. Eval (DataBinder.Eval) function is used to bind data in controls inside GridView, DataList, Repeater, DetailsView, etc. and using string.Format multiple values can be set to a single control.


Note that macros and string variables cannot have the same name. A macro is In all macro and string variable definitions, it is important to delay evaluation  Delayed variable expansion is often useful when working with FOR Loops, normally an entire FOR loop is evaluated as a single command even if it spans multiple lines of a batch script. This is the default behaviour of a FOR loop:


format or '%' strings and the rest annoyed when their code is constantly rejected in reviews because they don't know/care which standard to use where. aeturnum​  ANSWER: escape them with a backtick `” or use Here-Strings. A Here-String is a string which starts with a @” and ends with a “@ (on a line by itself). Here-Strings can use any character you want until it sees a “@ which terminates the string.


Seealso DaysInMonth(), FirstDayOfMonth() DE() Description: DE() stands for delay evaluation. Syntax: DE(String) Example: The following example uses DE​() to ensure that the string “A” is evaluated, instead of the variable “A”. is a simplified number formatting function that outputs numbers with two decimal places,  `string text` `string text line 1 string text line 2` `string text ${expression} string text` tag`string text ${expression} string text` Description Template literals are enclosed by the backtick (` `) ( grave accent ) character instead of double or single quotes.