angularjs - angularJS指令隔离范围声明中的 '=?'是什么意思？

等问后的问号有特殊含义吗？即:

scope: {foo: '=?'}

上面的意思是“无法解决'foo'时不会引发错误？”

最佳答案

Yes:



它应该在影响范围属性的每个摘要上触发预期的错误:

parentSet = parentGet.assign || function() {
// reset the change, or we will throw this exception on every $digest
lastValue = scope[scopeName] = parentGet(parentScope);
     throw Error(NON_ASSIGNABLE_MODEL_EXPRESSION + attrs[attrName] +
     ' (directive: ' + newScopeDirective.name + ')');
};

//...


if (parentValue !== scope[scopeName]) {
    // we are out of sync and need to copy
    if (parentValue !== lastValue) {
        // parent changed and it has precedence
        lastValue = scope[scopeName] = parentValue;
    } else {
        // if the parent can be assigned then do so
        parentSet(parentScope, lastValue = scope[scopeName]);
    }
}

关于angularjs - angularJS指令隔离范围声明中的 '=?'是什么意思？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20447786/