如何检查对象的键是否以特定字符开头？

Question

我只想检查对象键是否以特定的前缀开头。例如：

var obj = {
  456: "Hello",
  512: "Bye"
}

//what I want to do with the object

if (obj.key starts with 4) {
  // do this....
} else {
  // do this...
}

Answer 1

您可以获取密钥并对其进行测试。

var object = { 456:"Hello", 512:"Bye" },
    key;
    
for (key in object) {
    if (!key.startsWith('4')) continue;
    console.log(key, object[key]);
}

Answer 2

您可以使用Object.keys将对象转换为以键为元素的数组，并对其进行迭代，您可以使用4方法检查键是否以substr开头

var obj = {
  456: "Hello",
  512: "Bye"
}

Object.keys(obj)
      .forEach(e => e.substr(0, 1) == 4 ? console.log(e + ':' + obj[e]) : false)

Answer 3

您可以简单地使用startsWith

var obj = { 456:"Hello",  512:"Bye" }

Object.keys(obj).forEach(e => {
  e.startsWith('4') ?  console.log('start with 4 -->', e)
                    :  console.log('Do not start with 4 -->', e)
})

Answer 4

这有帮助吗？

var obj = {
  456: "Hello",
  512: "Bye"
}

Object.keys(obj).forEach(elem => {
  if (elem.charAt(0) == 4) {
    console.log(elem, obj[elem])
  }
  //else {}
});

Answer 5

您可以使用索引来读取字符串，就像读取数组一样：

var object = { 456 : "Hello", 512 : "Bye" };
for (var key in object) {
  if (key[0] === "4") {
    console.log(key + " starts with 4");
  } else {
    console.log(key + " does not start with 4");
  }
  console.log("object[" + key + "] gives \"" + object[key] + "\"");
}

Answer 6

Object.keys(total).filter(k => k.startsWith('your-specific-chars'))

Answer 7

var obj = { 
456:"Hello",
512:"Bye",
444:"good morning"
}


Object.keys(obj).forEach(function(key){
    if(key.startsWith('4'))
        console.log(key, obj[key]);

})

您可以尝试一下。