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| Template Literals |
Template Literals
Introduction:
When we want to use variable to make a string, it becomes very painful as we have to use + sign to concatenate and keep track of quotes.
Now with ES6,We can make string using backticks and using placeholders which are indicated with dollar sign and curly braces, like ${expression } .
const name='John';
const city='London';
Older Style:
const sentence ='My name is '+ name +'. I live in '+city.
ES6 way:
const sentence = `My name is ${name}. I live in ${city}`;
Here ${name} and ${city}are going to be interpolated by the variable name and city respectively.
MultiLine Strings:
Older style:
When we wanted to span our string into multiple lines, we had to use backslashes.
const multipleLineString= "We have \
multiple lines \
here";
Now when we want to create a mutiline string, we can make use of template strings.We can surround our string with backticks. This approach is extremely helpful when we want to create some dynamic html markup.
const htmlMarkup = `
<html>
<head></head>
<title>Template string</title>
<body>Hello World</body>
</html>`;
Nesting of Template Strings:
We can nest them inside of each other.
const cities =[
{name:'Delhi', year: 2010},
{name:'Mumbai', year: 2015},
{name:'Kolkata', year: 2017}];
const markup = `
<ul>
${cities.map(city=>`<li>I lived in ${city.name} in the year ${city.year}</li>`).join('')}
</ul>`;
Here the join operator after map function removes the extra commas which are added after each li.
If statements and Functions
We can also use If statements inside the template strings.
const data = {name: 'John', city: 'London', birthyear: 1900};
const markup = `<div>${data.name} lives in ${data.city}. ${data.birthyear ? `<div>He was born in the year ${data.birthyear}</div>`:''}</div>`;
In the example above, if birthyear is defined, then div with contents "He was born in the year" is generated otherwise there would be no div created.
We can also call functions inside the template strings.