onSelectionChanged(event) {
    let selectdata = event['api']['immutableService']['gridOptionsWrapper']['gridOptions']['rowData'];
    let selected_flag = 0;

    selectdata.forEach(data => {
      if (data.selected == true) {
        selected_flag = 1;
      }
    });

    if (selected_flag == 1) {
      this.showForms = true;
    } else {
      this.showForms = false;
    }
}

$scope.arr = [0, 1, 2];  
$scope.dict = {}
for ( var i=0; i < $scope.arr.length; i++ ) {
    if ( $scope.arr[i] == 1 ) {
        $scope.exists = 'yes, 1 exists';
        break;
    }
 }
 if ( $scope.exists ) {
     angular.forEach ( $scope.arr, function ( value, index ) {
                      $scope.dict[index] = value;
     });
 }

这是不可能的。见https://github.com/angular/angular.js/issues/263。取决于你在做什么，你可以使用布尔值来不进入循环体。喜欢的东西:

var keepGoing = true;
angular.forEach([0,1,2], function(count){
  if(keepGoing) {
    if(count == 1){
      keepGoing = false;
    }
  }
});

使用Return打破循环。

angular.forEach([0,1,2], function(count){
  if(count == 1) {
    return;
  }
});

onSelectionChanged(event) {
    let selectdata = event['api']['immutableService']['gridOptionsWrapper']['gridOptions']['rowData'];
    let selected_flag = 0;

    selectdata.forEach(data => {
      if (data.selected == true) {
        selected_flag = 1;
      }
    });

    if (selected_flag == 1) {
      this.showForms = true;
    } else {
      this.showForms = false;
    }
}

请使用ForEach的一些或所有实例，

Array.prototype.some:
some is much the same as forEach but it break when the callback returns true

Array.prototype.every:
every is almost identical to some except it's expecting false to break the loop.

例如:

var ary = ["JavaScript", "Java", "CoffeeScript", "TypeScript"];

ary.some(function (value, index, _ary) {
    console.log(index + ": " + value);
    return value === "JavaScript";
});

每个的例子:

var ary = ["JavaScript", "Java", "CoffeeScript", "TypeScript"];

ary.every(function(value, index, _ary) {
    console.log(index + ": " + value);
    return value.indexOf("Script") > -1;
});

查找更多信息 http://www.jsnoob.com/2013/11/26/how-to-break-the-foreach/