Moment JS日期时间比较

Question

I'm making an API call from a javascript function which is returning a JSON response correctly. But when stepping through the JSON response I'm getting a deprecation warning as well as an error at Function.createFromInputFallback (moment.js line:320) when I hit the line with moment().isSameOrBefore . I'm fairly new to javascript and especially the moment package for Node.

Basically, I would like to establish which predicted tide is the closest to the current time when this function is executed. Is this the correct way to use the moment().isSameOrBefore paramter and/or should I modify the code to go about this differently?

Here's the JSON:

{ "predictions" : [ {"t":"2018-06-08 03:06", "v":"3.795", "type":"H"},{"t":"2018-06-08 09:25", "v":"0.443", "type":"L"},{"t":"2018-06-08 15:51", "v":"3.884", "type":"H"},{"t":"2018-06-08 22:01", "v":"0.778", "type":"L"} ]}

Here's my function:

const getTide = require('./modules/getTide.js');

var moment = require('moment');

async function testMod() {
    await getTide.getQuote().then(function(value){
        const parsedData = JSON.parse(value);       
        let text = " "; 
        // This loop steps through the JSON response row by row to test the data
        var i;
        for (i = 0; i < parsedData.predictions.length; i++) { 
            text += 'Record #' + i + ' = ' + parsedData.predictions[i].t + " " + parsedData.predictions[i].v + " " + parsedData.predictions[i].type + " - ";            
            let curDateTime = moment().format('LLL');           
            let theDate = moment(parsedData.predictions[i].t).format('LLL'); 
            let fromNow = moment(parsedData.predictions[i].t).fromNow(); 
            if (parsedData.predictions[i].type === "H") {
                    console.log('High tide for ' + parsedData.predictions[i].t + ', at ' + parsedData.predictions[i].v + ' vertical Feet. ');                                  
                    if (moment(theDate).isSameOrBefore(curDateTime)) {
                       console.log('It is currently ' + curDateTime + ' and that high tide was ' + fromNow);
                    } else {
                       console.log('It is currently ' + curDateTime + ' and that high tide is ' + fromNow + ' from now!');  
                    }                   
                  } else {
                    console.log('Low tide for ' + parsedData.predictions[i].t + ', at ' + parsedData.predictions[i].v + ' vertical Feet. ');
                    if (moment(theDate).isSameOrBefore(curDateTime)) {
                       console.log('It is currently ' + curDateTime + ' and that low tide was ' + fromNow);
                    } else {
                       console.log('It is currently ' + curDateTime + ' and that low tide is ' + fromNow + ' from now!');   
                    }               
                  }     
        }
    }, function(error){
        console.log("problem");
    });
}

testMod();

Answer 1

I think part of the issue is you're using formatted strings to create moment instances instead of just using the moment instance itself. So instead of doing this:

let curDateTime = moment().format('LLL');           
let theDate = moment(parsedData.predictions[i].t).format('LLL'); 
// ...
moment(theDate).isSameOrBefore(curDateTime);

Try:

let curDateTime = moment();
let theDate = moment(parsedData.predictions[i].t);
// ...
theDate.isSameOrBefore(curDateTime); // because theDate is now a moment instance, you can call this function on it

When working with moment, it's always a good idea to keep your datetimes stored as moment instances until you need to display them to the user, then you can go ahead and do:

theDate.format('LLL');

I think the warning you are getting is because you are trying to create a moment instance with a string in the 'LLL' format which moment is complaining about ("Deprecation warning: value provided is not in a recognized RFC2822 or ISO format." is the warning I am seeing). If you wanted to parse these formats you have to specify the format as well:

moment('September 4, 1986 8:30 PM', 'LLL').format('YYYY-MM-DD H:mm'); // won't complain