Talking about ES15: strings

2015-08-251 Min Read — In code

There are a few new features related to strings in ES2015. They're easy to learn and they allow for a more clean code.

In ES15, some new methods were added to the String object. For instance, now there's a repeat method.

var tripleX = "X".repeat(3);
console.log(tripleX); // XXX

Instead of checking the indexOf to verify if a string contains some text, we can now use the includes method.

console.log("JavaScript".includes("ava")); // true
console.log("JavaScript".includes("hello")); // false

We can verify if a string starts with or ends with some text.

console.log("Luke".startsWith("Lu")); // true
console.log("Leia".endsWith("ia")); // true

For all of those three methods (includes, startsWith and endsWith), there's an optional second parameter used to specify where in the string the search starts.

console.log("The blue pill".includes("blue", 4)); //true
console.log("The red pill".startsWith("red", 4)); //true
console.log("Hello Mr. Anderson".endsWith("Hello Mr", 8)); //true

Template literals

Template literals are a new string literal which we can have multiple lines and we also can interpolate expressions.

let name = "Thiago";
console.log(`Hello ${name}`); // Hello Thiago

let message = `Hello 
${name}, 
welcome to ES2015`;

console.log(message);
// Hello
// Thiago
// welcome to ES2015

Note that to delimit the literal we use backticks (`) and not single quotes, and all interpolated expressions are delimited by ${}.

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