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    label

    Summary

    The labeled statement can be used with break or continue statements. It is prefixing a statement with an identifier which you can refer to.

    Syntax

    label :
       statement
    
    label
    Any JavaScript identifier that is not a reserved word.
    statement
    Statements. break can be used with any labeled statement, and continue can be used with looping labeled statements.

    Description

    You can use a label to identify a loop, and then use the break or continue statements to indicate whether a program should interrupt the loop or continue its execution.

    Note that JavaScript has NO goto statement, you can only use labels with break or continue.

    Avoid using labels

    Labels are not very commonly used in JavaScript since they make programs harder to read and understand. As much as possible, avoid using labels and, depending on the cases, prefer calling functions or throwing an error.

    Examples

    Using a labeled continue with for loops

    var i, j;
    
    loop1:
    for (i = 0; i < 3; i++) {      //The first for statement is labeled "loop1"
       loop2:
       for (j = 0; j < 3; j++) {   //The second for statement is labeled "loop2"
          if (i == 1 && j == 1) {
             continue loop1;
          }
          console.log("i = " + i + ", j = " + j);
       }
    }
    
    // Output is:
    //   "i = 0, j = 0"
    //   "i = 0, j = 1"
    //   "i = 0, j = 2"
    //   "i = 1, j = 0"
    //   "i = 2, j = 0"
    //   "i = 2, j = 1"
    //   "i = 2, j = 2"
    // Notice how it skips both "i = 1, j = 1" and "i = 1, j = 2"
    

    Using a labeled continue statement

    Given an array of items and an array of tests, this example counts the number of items that passes all the tests.

    var itemsPassed = 0;
    var i, j;
    
    top:
    for (i = 0; i < items.length; i++){
      for (j = 0; j < tests.length; j++)
        if (!tests[j].pass(items[i]))
          continue top;
        itemsPassed++;
    }

    Using a labeled break with for loops

    var i, j;
    
    loop1:
    for (i = 0; i < 3; i++) {      //The first for statement is labeled "loop1"
       loop2:
       for (j = 0; j < 3; j++) {   //The second for statement is labeled "loop2"
          if (i == 1 && j == 1) {
             break loop1;
          }
          console.log("i = " + i + ", j = " + j);
       }
    }
    
    // Output is:
    //   "i = 0, j = 0"
    //   "i = 0, j = 1"
    //   "i = 0, j = 2"
    //   "i = 1, j = 0"
    // Notice the difference with the previous continue example

    Using a labeled break statement

    Given an array of items and an array of tests, this example determines whether all items pass all tests.

    var allPass = true;
    var i, j;
    
    top:
    for (i = 0; items.length; i++)
      for (j = 0; j < tests.length; i++)
        if (!tests[j].pass(items[i])){
          allPass = false;
          break top;
        }

    Specifications

    Specification Status Comment
    ECMAScript 3rd Edition Standard Initial definition. Implemented in JavaScript 1.2
    ECMAScript 5.1 (ECMA-262)
    The definition of 'Labelled statement' in that specification.
    Standard  
    ECMAScript 6 (ECMA-262)
    The definition of 'Labelled statement' in that specification.
    Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Last updated by: fscholz,
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