是否可以通过一个键数组在对象中设置变量? 例如,我有这个对象:
var obj = {'outer': {'inner': 'value'} };
我想根据一个键的数组设置所选的值:
var keys = ['outer', 'inner'];
为了得到这个结果,将值更改为'newValue'
obj = {'outer': {'inner': 'newValue'} };
是否可以通过一个键数组在对象中设置变量? 例如,我有这个对象:
var obj = {'outer': {'inner': 'value'} };
我想根据一个键的数组设置所选的值:
var keys = ['outer', 'inner'];
为了得到这个结果,将值更改为'newValue'
obj = {'outer': {'inner': 'newValue'} };
function setVal(obj, keys, value) {
var o = obj,
len = keys.length;
// iterate through all keys, making sure each key exists and points to an object
for (var i = 0; i < len - 1; i++) {
var key = keys[i];
// check if the current key exists and is an object
if (obj.hasOwnProperty(key) && typeof obj[key] === 'object' && obj[key]) {
o = o[key];
} else {
// return false or throw an error cause the key is not an object or is missing.
}
}
// update the value at the last key
o[keys[len - 1]] = value;
}
function setVal(obj, keys, value) {
var o = obj,
len = keys.length;
for (var i = 0; i < len - 1; i++) {
var key = keys[i];
if (obj.hasOwnProperty(key) && typeof obj[key] === 'object' && obj[key]) {
o = o[key];
} else {
throw new Error('Key ' + key + ' is not an object or is missing.');
}
}
o[keys[len - 1]] = value;
}
var obj = {
'outer': {
'inner': 'value'
}
};
var validKeys = ['outer', 'inner'];
var invalidKeys = ['outer', 'inner', 'extra'];
console.log('Setting valid keys');
setVal(obj, validKeys, 'new value');
console.log(obj);
console.log('Setting invalid keys');
setVal(obj, invalidKeys, 'new value');
console.log(obj);
hasOwnProperty
将最后一条语句包装在 setVal
中:// if object already has the last key, update its value
if (o.hasOwnProperty(keys[len - 1])) {
o[keys[len - 1]] = value;
} else {
// throw an error or return false since the last key doesn't exist.
}
obj.prop
与obj["prop"]
等效。function SetValueByKeyNames(obj, keys, value) {
var target = obj;
for(var i = 0; i < keys.length - 1; i++) {
target = target[keys[i]];
if (!target)
return false;
}
target[keys[keys.length - 1]] = value;
return true;
}
var obj = {'outer': {'inner': 'value'} };
var keys = ['outer', 'inner'];
console.log(obj.outer.inner); // value
SetValueByKeyNames(obj, keys, 'newValue');
console.log(obj.outer.inner); // newValue