问题
I have an angular foreach loop and i want to break from loop if i match a value. The following code does not work.
angular.forEach([0,1,2], function(count){
if(count == 1){
break;
}
});
How can i get this?
回答1:
There's no way to do this. See https://github.com/angular/angular.js/issues/263. Depending on what you're doing you can use a boolean to just not going into the body of the loop. Something like:
var keepGoing = true;
angular.forEach([0,1,2], function(count){
if(keepGoing) {
if(count == 1){
keepGoing = false;
}
}
});
回答2:
The angular.forEach loop can't break on a condition match.
My personal advice is to use a NATIVE FOR loop instead of angular.forEach.
The NATIVE FOR loop is around 90% faster then other for loops.
USE FOR loop IN ANGULAR:
var numbers = [0, 1, 2, 3, 4, 5];
for (var i = 0, len = numbers.length; i < len; i++) {
if (numbers[i] === 1) {
console.log('Loop is going to break.');
break;
}
console.log('Loop will continue.');
}
回答3:
please use some or every instances of ForEach,
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.
Example for some:
var ary = ["JavaScript", "Java", "CoffeeScript", "TypeScript"];
ary.some(function (value, index, _ary) {
console.log(index + ": " + value);
return value === "JavaScript";
});
Example for every:
var ary = ["JavaScript", "Java", "CoffeeScript", "TypeScript"];
ary.every(function(value, index, _ary) {
console.log(index + ": " + value);
return value.indexOf("Script") > -1;
});
Find more information
http://www.jsnoob.com/2013/11/26/how-to-break-the-foreach/
回答4:
Use the Array Some Method
var exists = [0,1,2].some(function(count){
return count == 1
});
exists will return true, and you can use this as a variable in your function
if(exists){
console.log('this is true!')
}
Array Some Method - Javascript
回答5:
As far as I know, Angular doesn't provide such a function. You may want to use underscore's find() function for this (it's basically a forEach which breaks out of the loop once the function returns true).
http://underscorejs.org/#find
回答6:
If you use jQuery (hence not jqLite) in conjunction with AngularJS you can iterate with $.each - which allows breaking and continuing based on boolean return value expression.
JSFiddle:
http://jsfiddle.net/JEcD2/1/
Javascript:
var array = ['foo', 'bar', 'yay'];
$.each(array, function(index, element){
if (element === 'foo') {
return true; // continue
}
console.log(this);
if (element === 'bar') {
return false; // break
}
});
Note:
Though using jQuery is not bad, both native Array.some or Array.every functions are recommended by MDN as you can read at native forEach documentation:
"There is no way to stop or break a forEach loop. The solution is to use Array.every or Array.some"
Following examples are provided by MDN:
Array.some:
function isBigEnough(element, index, array){
return (element >= 10);
}
var passed = [2, 5, 8, 1, 4].some(isBigEnough);
// passed is false
passed = [12, 5, 8, 1, 4].some(isBigEnough);
// passed is true
Array.every:
function isBigEnough(element, index, array){
return (element >= 10);
}
var passed = [12, 5, 8, 130, 44].every(isBigEnough);
// passed is false
passed = [12, 54, 18, 130, 44].every(isBigEnough);
// passed is true
回答7:
Concretely, you can exit of a forEach loop, and of any place, throw an exception.
try {
angular.forEach([1,2,3], function(num) {
if (num === 2) throw Error();
});
} catch(e) {
// anything
}
However, it is better if you use other library or implement your own function, a find function in this case, so your code is most high-level.
回答8:
Try this as break;
angular.forEach([0,1,2], function(count){
if(count == 1){
return true;
}
});
回答9:
As the other answers state, Angular doesn't provide this functionality. jQuery does however, and if you have loaded jQuery as well as Angular, you can use
jQuery.each ( array, function ( index, value) {
if(condition) return false; // this will cause a break in the iteration
})
See http://api.jquery.com/jquery.each/
回答10:
Normally there is no way to break an "each" loop in javascript. What can be done usually is to use "short circuit" method.
array.forEach(function(item) {
// if the condition is not met, move on to the next round of iteration.
if (!condition) return;
// if the condition is met, do your logic here
console.log('do stuff.')
}回答11:
break isn't possible to achieve in angular forEach, we need to modify forEach to do that.
$scope.myuser = [{name: "Ravi"}, {name: "Bhushan"}, {name: "Thakur"}];
angular.forEach($scope.myuser, function(name){
if(name == "Bhushan") {
alert(name);
return forEach.break();
//break() is a function that returns an immutable object,e.g. an empty string
}
});
回答12:
You can use this:
var count = 0;
var arr = [0,1,2];
for(var i in arr){
if(count == 1) break;
//console.log(arr[i]);
}
回答13:
var ary = ["JavaScript", "Java", "CoffeeScript", "TypeScript"];
var keepGoing = true;
ary.forEach(function(value, index, _ary) {
console.log(index)
keepGoing = true;
ary.forEach(function(value, index, _ary) {
if(keepGoing){
if(index==2){
keepGoing=false;
}
else{
console.log(value)
}
}
});
});
回答14:
$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;
});
}
回答15:
I would prefer to do this by return. Put the looping part in private function and return when you want to break the loop.
回答16:
I realise this is old, but an array filter may do what you need:
var arr = [0, 1, 2].filter(function (count) {
return count < 1;
});
You can then run arr.forEach and other array functions.
I realise that if you intend to cut down on loop operations altogether, this will probably not do what you want. For that you best use while.
回答17:
This example works. Try it.
var array = [0,1,2];
for( var i = 0, ii = array.length; i < ii; i++){
if(i === 1){
break;
}
}
回答18:
Use Return to break the loop.
angular.forEach([0,1,2], function(count){
if(count == 1) {
return;
}
});
回答19:
I would use return instead of break.
angular.forEach([0,1,2], function(count){
if(count == 1){
return;
}
});
Works like a charm.
回答20:
Just add $index and do the following:
angular.forEach([0,1,2], function(count, $index) {
if($index !== 1) {
// do stuff
}
}
来源：https://stackoverflow.com/questions/13843972/angular-js-break-foreach