What browsers currently support JavaScript's 'let' keyword?

Question

I\'m developing an app and don\'t have to ever worry about Internet Explorer and was looking into some of the features present in A+ grade browsers that aren\'t in Inte

Answer 1

As of April 2017:

• All up-to-date major browsers such as Chrome, Firefox, and Edge support the ES2015 (aka "ES6") let keyword.

• iOS Safari did not support let until OS 10 (e.g, OS 9 did not).

• Some older browsers, such as IE9-IE11, support an early version of let but don't support the semantics defined by ES2015 (particularly in relation to declarations in the headers of for loops). So it's not a syntax error, and it does declare the variable, but it doesn't work the way it's supposed to. For instance, in a correct implementation, the following logs 0, 1, and 2; on IE9-IE11, it logs 3, 3, 3:

   for (let i = 0; i < 3; ++i) {
        setTimeout(function() {
            console.log(i);
         }, i * 100);
    }
   

• Obsolete browsers such as IE8 do not support it at all.