Can anyone help me decipher this function?

We are currently working on a small project, we are updating and adding some feature to an existing software and we came across this function that we don't have any idea of what it does.

function myRange(a){var b=false;b=MinMax(a,83300000,83399999,b);b=MinMax(a,83500000,83599999,b);b=MinMax(a,83600000,83699999,b);b=MinMax(a,84000000,84099999,b);b=MinMax(a,84100000,84189999,b);b=MinMax(a,84190000,84199999,b);b=MinMax(a,84200000,84249999,b);b=MinMax(a,84250000,84499999,b);b=MinMax(a,84900000,84983599,b);b=MinMax(a,84983600,84999999,b);b=MinMax(a,86000000,86699999,b);b=MinMax(a,86900000,86999999,b);b=MinMax(a,87400000,87409999,b);b=MinMax(a,88200000,88599999,b);b=MinMax(a,89000000,89499999,b);b=MinMax(a,87300000,87399999,b);b=MinMax(a,22634000,22634999,b);b=MinMax(a,22635000,22635999,b);b=MinMax(a,23139000,23139999,b);b=MinMax(a,23449000,23449999,b);b=MinMax(a,27197000,27197999,b);b=MinMax(a,27226000,27226999,b);b=MinMax(a,27379000,27379999,b);b=MinMax(a,27845000,27845999,b);b=MinMax(a,87200000,87299999,b);b=MinMax(a,87437000,87437999,b);if(b==false){dojo.byId开发者_StackOverflow社区("destino").value="";dojo.byId("destino").focus()}}function MinMax(c,a,d,b){if((c<=d)&&(c>=a)){b=true;return b}else{return b}};

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The myRange function tests whether its argument a lies within any of the ranges 83300000..83399999, 83500000,83599999, etc.; after all those MinMax calls, b is true if a was within one of the ranges and false otherwise.