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javascripttemplate-strings

Why use the templatestring expression a=`${a}` in javascript?

I was looking at some javascript code and noticed a line using the template string backticks:

a=`${a}`

However, this does not seem to have any effect to me as the variable a contains a string.

Is this simply a NOP or is there string value for a that would make the result differ from the original value?

Solution

  • If a is not a string, doing this will convert the variable to a string, by invoking the .toString() available on the object's prototype:

    function templateString(d) {
  return `${d}`;
}

console.log(templateString('foo bar'));
console.log(templateString(1337));
console.log(templateString(false));
console.log(templateString(undefined));
console.log(templateString({ 'foo': 1337, 'bar': 'baz' }));
console.log(templateString(['foo', 'bar', 'baz']));
console.log(templateString(function(x) { return x; }));
console.log(templateString(new RegExp('\\w+')));