JavaScript break specify label breaking multi-layer Loop example

The syntax of a break has two kinds of break; and break label; let's introduce you to break the whole loop nested example

Today, when reading the JavaScript Authority Guide, we found that there are two kinds of break syntax (break; and break label;    Never looked carefully, on the first few pages. But do not understand how to write label, so the internet search, found an example code as follows: function foo () {dance:for (var k = 0; k < 4; k++) {for (var m = 0; m < 4;  m++) {if (M = = 2) {break dance;    }}} So you can break the entire loop nesting!! (C,java's break is like this, reading is not serious ah ...) ）