ChartJS remove vertical grid lines one on two - chart.js

Question

I have the below ChartJS code and I would like to hide the grid vertical lines only and not the horizontal ones and keep only one vertical line per two like in the capture below:
image]1
Thanks.
<canvas id="line-chart" width="800" height="450"></canvas>
new Chart(document.getElementById("line-chart"), {
type: 'line',
data: {
labels: [1500,1600,1700,1750,1800,1850,1900,1950,1999,2050],
datasets: [{
data: [86,114,106,106,107,111,133,221,783,2478],
label: "Africa",
borderColor: "#3e95cd",
fill: false
}, {
data: [282,350,411,502,635,809,947,1402,3700,5267],
label: "Asia",
borderColor: "#8e5ea2",
fill: false
}, {
data: [168,170,178,190,203,276,408,547,675,734],
label: "Europe",
borderColor: "#3cba9f",
fill: false
}, {
data: [40,20,10,16,24,38,74,167,508,784],
label: "Latin America",
borderColor: "#e8c3b9",
fill: false
}, {
data: [6,3,2,2,7,26,82,172,312,433],
label: "North America",
borderColor: "#c45850",
fill: false
}
]
},
options: {
title: {
display: true,
text: 'World population per region (in millions)'
}
}
});

Answer 1

Just add grid color as function in options for x axis scale and conditionally change the colors like its done below:
var chartInstance = new Chart(document.getElementById("chartJSContainer"), {
type: 'line',
data: {
labels: [1500, 1600, 1700, 1750, 1800, 1850, 1900, 1950, 1999, 2050],
datasets: [{
data: [86, 114, 106, 106, 107, 111, 133, 221, 783, 2478],
label: "Africa",
borderColor: "#3e95cd",
fill: false
}, {
data: [282, 350, 411, 502, 635, 809, 947, 1402, 3700, 5267],
label: "Asia",
borderColor: "#8e5ea2",
fill: false
}, {
data: [168, 170, 178, 190, 203, 276, 408, 547, 675, 734],
label: "Europe",
borderColor: "#3cba9f",
fill: false
}, {
data: [40, 20, 10, 16, 24, 38, 74, 167, 508, 784],
label: "Latin America",
borderColor: "#e8c3b9",
fill: false
}, {
data: [6, 3, 2, 2, 7, 26, 82, 172, 312, 433],
label: "North America",
borderColor: "#c45850",
fill: false
}]
},
options: {
title: {
display: true,
text: 'World population per region (in millions)'
},
scales: {
x: {
grid: {
display: true, //Make it false to remove all the vertical lines.
color: function(context) {
if (context.tick.value %2 == 0) {
return 'gray';
} else {
return 'white';
}
},
}
}
}
}
});
<script src="https://cdn.jsdelivr.net/npm/chart.js#3.3.1/dist/chart.js"></script>
<canvas id="chartJSContainer" width="600" height="400"></canvas>

Answer 2

I don’t really use chart.js so there may be a better way to do this. I think there may be a built in way to use a callback for this but I couldn’t figure it out. Here’s what does work.
Add this function at the top to create an array of alternating colors.
let colors = [];
function gridColors() {
for (let i=0; i<10; i++) {
colors.push("rgba(0,0,0,0)")
colors.push("rgba(0,0,0,0.1)")
}
}
gridColors()
And in your options add the following
options: {
title: {
display: true,
text: 'World population per region (in millions)'
},
scales: {
x: {
grid: {
beginAtZero: true,
color: colors,
}
}
}
}
});