Chapter 11th Subset and extension of JavaScript

11.1 A subset of JavaScript

　　11.1.1 Essence

　　Security of 11.1.2 subsets

11.2 Constants and local variables

<script type= "Text/javascript" >//keyword let has 4 ways to use    //can be declared as a variable, as with Var    //in the For or for/in loop, as a substitute for Var    //defines a new variable in a statement block and displays the scope that specifies it    //defines a variable within the scope of an expression that is only available in an expression    functionoddsum (n) { let total= 0, result = [];  for(Let x = 1; x <= n;x++) {Let odd= 2 * x-1; Total+=Odd;        Result.push (total); }        returnresult; }    //Console.log (total);//referencerrrorConsole.log (Oddsum (5));</script>

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11.3 Deconstruction Assignment

<script type= "Text/javascript" >    // deconstructed Assignment (destructuring Assignment)let    [x, y] = [+];  // Let x=1,y=2    [x, Y] = [× + 1,y + 1];  // x = x + 1,y = y + 1    [x, Y] = [y,x];    Console.log ([x, y]); </script>

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11.4 iterations

　　11.4.1 For/each Cycle

<script type= "Text/javascript" >    = {one:1,two:2,three:3}    for in o) {        console.log (p);    }     // For each (let V in O) {    //     Console.log (v);    // }</script>

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　　11.4.2 iterators

<script type= "Text/javascript" >    Function  counter (start) {        = math.round (start);         returnfunctionreturn nextvalue++;}};    }     = Counter (+);     = Serialnumbergenerator.next ();     = Serialnumbergenerator.next (); </script>

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　　11.4.3 Generator

<script type= "Text/javascript" >    // Generator is an object that represents the current execution state of the generator function /    *     function Range (Min,max) {for        (Let i = Math.ceil (min); I <= max;i++) {            yield i;        }    }    for (Let N in range (3,8)) {        console.log (n);    }     */</script>

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　　11.4.4 Array Derivation

<script type= "Text/javascript" >//JavaScript1.7    //array derivation is a technique for initializing array elements using another array or an iterative object .    //Let evensquares = [x*x for (x in range (0,10)) if (x 2 = = = 0)];    //Let evensquares = [];    //For (x in range (0,10)) {    //if (x% 2 = = = 0) {    //Evensquares.push (x*x);    //    }    //}    //[expression for (variable in object) if (condition)]</script>

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　　11.4.5-Generator expression

<script type= "Text/javascript" >    /leth = (f (x) for (x in G));    // Let lines = eachline (text);    // Let trimmed = (L.trim () for (L in lines));    // Let nonblank = (L-in trimmed) if (l.length > 0 && l[0]! = ' # ')); </script>

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11.5 Shorthand for functions

<script type= "Text/javascript" >    // for simple functions, JavaScript1.8 introduces a shorthand form: expression closure     functionfunctiontruefunctionfalse; </script>

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11.6 Multiple Catch clauses

<script type= "Text/javascript" >/    *    try {        throw 1;    }    catch (E if e instanceof referenceerror) {    }    catch (e if E = = = "Quit") {    }    catch (e if typeof e = = = "str ing ") {    }    catch (e) {    }    finally {    }    */</script>

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11.7 E4x:ecmascript for XML

Chapter 11th Subset and extension of JavaScript