How to interpolate variables in strings in JavaScript, without concatenation?
Prior to Firefox 34 / Chrome 41 / Safari 9 / Microsoft Edge, nope, that was not possible in javascript. You would have to resort to:
var hello = "foo";
var my_string = "I pity the " + hello;
Prior to Firefox 34 / Chrome 41 / Safari 9 / Microsoft Edge, no. Although you could try sprintf for JavaScript to get halfway there:
var hello = "foo";
var my_string = sprintf("I pity the %s", hello);
You can take advantage of Template Literals and use this syntax:
`String text ${expression}`
Template literals are enclosed by the back-tick (` `) (grave accent) instead of double or single quotes.
This feature has been introduced in ES2015 (ES6).
Example
var a = 5;
var b = 10;
console.log(`Fifteen is ${a + b}.`);
// "Fifteen is 15.
How neat is that?
Bonus:
It also allows for multi-line strings in javascript without escaping, which is great for templates:
return `
<div class="${foo}">
...
</div>
`;
Browser support:
As this syntax is not supported by older browsers (mostly Internet Explorer), you may want to use Babel/Webpack to transpile your code into ES5 to ensure it will run everywhere.
Side note:
Starting from IE8+ you can use basic string formatting inside console.log
:
console.log('%s is %d.', 'Fifteen', 15);
// Fifteen is 15.